Ryan Stark | Blackstone Laboratories

About Ryan Stark

Ryan started at Blackstone in 1997 after graduating from Purdue University with a degree in mechanical engineering. Ryan is responsible for writing and maintaining Blackstone's software program, setting up and managing the lab, writing reports, and a million other things that need to be done in a business. When he's not kicking ass in the lab or writing code, Ryan enjoys putting his pilot's license to good use, working on his '84 Chevy 3/4 ton, and raising his kids. As an experiment, Ryan ran Aeroshell W65 — an oil with no zinc or phosphorus in it — in his Chevy to determine if the hype over ZDDP (zinc dithiophosphate) is all that or not, figuring if the experiment ruined his engine, well, he's rebuilt it before. (Spoiler alert: The engine was fine. To read about the endeavor and see pictures from the rebuild, read the article "Rebuilding a GM 350 Engine.")

How Often Should I Sample?

One of the most common questions we get asked is, “How often should I send in a sample?” and this is one that I tend to struggle with answering.

The businessman in me says at every oil change regardless, and while you’re at it, check your transmission fluid, differential fluid, and your wife’s/husband’s car. And don’t forget any air compressors, lawn mowers, wood splitters, etc. you may own. And your neighbor’s car was smoking a bit last time you saw it drive past, better check that too.

Unfortunately, before I start talking, my “realist” side kicks in and I usually say something like once a year, after you have some good trends established. But even that answer doesn’t always apply. What if you don’t drive your vehicle very often, or at all? Is it really necessary to test the oil once a year? The answer to that is once again not really. Though if you think you might have a problem developing, then it could be a good idea to sample more often than you normally would.

Old oil

We recently had a customer send in a sample of oil that was in an engine for 10 years and had not been run at all in more than 5 years — and amazingly enough wear metals were virtually identical to what we were seeing when he last sampled 10 years ago.

The only significant difference was at insolubles. These had gone from 0.2% to 0.0% after the 5 years of sitting. We figured the reason for this was gravity. All normal engine oils contain dispersant additives, and their function is to hold dirt and solids in suspension so they can be filtered out. Do they work? Absolutely, but asking them to work for a full five years is a little much. The good news is that the additives are still in the oil, so once the engine starts up and sees some use, those solids should be picked up and dispersed again.

So, if we can say with good certainty that the oil itself won’t go bad just sitting in an engine, you might wonder why it needs to be changed at all? The answer to that is contamination.

Contamination problems

Engine oil has maybe the hardest life of any oil application out there. Not only does it see frequent temperature swings of 150° to 200°F (65° to 90°C), but it will also get contaminated with fuel blow-by and a little atmospheric water as well.

Ideally the fuel and water will boil out once the oil gets up to operating temperature, but that contamination will add up over time and eventually cause the oil to start to oxidize. If you can pinpoint exactly when the oil will oxidize enough that it will start to affect wear or cause the oil’s viscosity to change, that’s the point at which you want to change the oil. If you test your oil on a regular basis, you can start to identify that point and that’s one of the reasons why we’re here.

So when is the best time to get a sample? The answer to that is: it depends.

Best time to sample?

If you just bought a brand-new car, the first oil is factory oil and while that oil will sometimes have an unusual additive package, it’s not that useful for finding a problem, or developing a normal wear trend.

Factory oil is typically loaded with excess metal from wear-in of new parts as well and some silicon from sealers used when the engine was assembled, and this stuff normally takes two or three oil changes to wash out.

So, while these samples aren’t useful as far as trends go, they are useful in finding problems in engines that have been recently rebuilt or had other major work done, and we always recommend testing those from the beginning. This is because if wear metals don’t drop from that initial oil fill, it can be the early indication of a problem.

It’s always a good idea to get a trend going while the engine is running well. A trend consists of three samples. Once we have that established and the engine is running perfectly, then it’s not really necessary to get a sample at each oil change and at that point it’s okay in most cases to go to a once-a-year sampling routine.

Once a year?

You might be wondering why once a year? The reason for that is two-fold. One: A lot of people (including myself) only change their oil once a year. It’s also the only time I crawl under my car and have the hood open. I consider it like an annual inspection and there are been numerous times that I have been on my back waiting for the oil to drain when I noticed another problem like a seeping freeze-plug or a torn CV boot. Two: It’s easy to remember.

However, the once-a-year rule doesn’t always apply. There are many vehicles out there that only see light use (maybe less than 500 miles a year), so not only can they typically skip changing oil on a yearly basis, then don’t need to sample every year.

Another factor is how important the vehicle is to you. If you rely on it for your business, or it’s the only vehicle you have and it’s getting up there in mileage, then sampling at every oil change might be a very good idea.

Engines speak before they fail

We can see problems developing in your engine long before they actually cause a failure, so you normally have some time to do something about any trouble we might spot. Still, like a lot of things in life, the earlier you know about problems the better.

We get as lot of samples from engines that have a known problem, so we test the oil and usually see poor wear, but telling how bad the problem is or how/when it started is hard without trends from when the engine was normal. We do have averages that give us a good idea how an engine should look overall, but they aren’t as valuable as trends when it comes to saying exactly what’s normal for a particular engine and the use it sees.

So there you have it, I’m actually saying you may not need our services as much as you might think. Some of the other business owners out there might call me crazy and I guess they’re right. But please, feel free to sample anytime you like. As you know there is nothing better than getting a glowing oil report on your pride and joy.

By Ryan Stark|2026-01-19T14:25:53-05:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

Viscosity: Going Down!

April of 2017 will mark my 20^th year here at Blackstone and in that time a lot of changes have taken place. I’m a big fan of change myself and long ago got some advice from my Uncle Dan who said, “The only thing that’s constant in life is change.” I decided that his words were the truth, and it seems to me like change should be embraced because there is no stopping it, and also for the most part change is good. It might not seem good on the outset, but if you give it some time, things eventually work out. After a bit of reflection on the changes in the oil industry, I’ve decided that one of the best ones has been the trend to lower viscosity oils.

The thin oil trend

I started changing my own oil on a regular basis in the early ’90s, and at that time 10W/30 was the oil of choice in my 1981 Chevy Citation. I didn’t think that much about it. It said right on the oil cap use 10W/30, so I bought whatever was on sale and went along fat, dumb, and happy.

At that time 5W/30 oil was starting to be as common as 10W/30 on the shelves, but I never went with it because it wasn’t what GM said to use. However, my wife’s first car (1994 Buick Skylark) recommended 5W/30, so that was a sign that thinner oils were starting to come into favor. Again, I didn’t think much about it, and basically just stuck with what was recommended when I changed her oil.

Then, in the early 2000s I noticed that we were starting to see a lot of samples from Ford V-8 engines that were running 5W/20 oil. This was a bit of a surprise since that’s pretty thin oil, but it was hard to argue with the results. Those engines produced some of the best wear we would see on a regular basis, so it quickly because obvious to me that this was a change for the better. And if you think about it, it makes sense.

Wear at start-up

For years, it was taken as fact by a lot of people that most of the wear in an engine happens at start-up. Now I haven’t done any studies myself to see if that was true, but that statement didn’t seem out of line from what I know about engines.

So assuming it’s true, why would just starting an engine cause wear? Well, I believe the answer is the oil isn’t flowing over all of the parts like it does shortly after start-up. I do know that engines have virtually no metals parts touching one another without a thin film of oil providing a lubrication barrier, at least once oil pressure has been established. I also know that thin oil pumps easier than thick oil, so it’s seems obvious that the quicker you can get the oil to the parts, the less wear an engine will produce. From then on I was sold on thin oil.

So what’s the problem here? Well, when I first started at Blackstone, I was told that thick oil is good for the bearings, and I didn’t have cause to doubt that statement until I saw these Ford V-8s producing virtually no wear, and I knew some of them were work trucks that were hauling heavy loads. So could it be that the bearings didn’t need thin oil to survive? The answer is a resounding yes.

Even for diesels?

That trend toward thinner oil has proven true everywhere except for diesel engines. For years and years and even today, the oil of choice in a diesel was/is 15W/40. But, if a heavy-duty gas engine can run light oil, why can’t a diesel?

We would occasionally see diesel samples from Alaska that were running 5W/30 and they would look fine, so why not use it down here in the lower 48? In colder weather, it was acceptable for diesel to run thin oil, but that really only matters on start-up. But the oil doesn’t get thicker as it heats up¾it thins out.

So could it be that thin oil does fine even when it get gets up to operating temperature? The answer to me was another resounding yes, and I wondered when the day would come that 15W/40 would not longer be the manufacturer’s choice foe diesel engines. Well, that change has come!

Today we are starting to see more diesel fleets going to 10W/30, and I’m here to tell you that this change is good. Not only will the bearings do just fine, but the engines will start up better (especially in the cold). Now, there will always be some people who are resistant to change. In fact that are whole countries that are. The German vehicle manufacturers have yet to embrace thin oil, though I think that change will happen someday.

Yes, change is good and I have yet to see a change happen that leaves hundreds of thousands vehicles stuck along the side of the road. The sulfur has been virtually removed from diesel fuel and your old tractor still runs fine* (if this statement makes you mad, see my note below). Additive levels have been lowered in engine oil and the old flat-tappet engines still run great. And now thinner oils are here to stay. I’m excited to see what the changes the next 20 years might bring and I believe that I’ll embrace it, unless it involves getting rid of oil altogether!

*Note: Don’t get mad at me. I wasn’t in charge of that change and your injectors/fuel pump were probably on their way out anyway!

By Ryan Stark|2026-01-19T14:26:04-05:00July 28, 2023|Articles, Gas/Diesel Engine, Lab Tests|Comments Off

This Ain’t Your Daddy’s ATF

It’s been a while since we wrote about transmissions: how they work, the differences between manual and automatic transmissions, and what transmission oil looks like. Since that time, a fair amount has changed in the transmission world, both in the machines themselves and the oil they use, as well as our knowledge on the subject. “Lifetime” transmission fluids are pretty common now, as are CVT (continuously variable transmission) units. Transmission oil has changed too, with certain transmissions requiring special oils, so we thought it was high time for an update.

Learning how newer transmissions work

While manual transmissions are fairly simple machines that tend to run forever, automatic and CVT transmissions are more mysterious in how they work.

When we hire new report writers, training them on the ins and outs of transmissions and transmission oil takes quite a bit of time and a lot of internet searching to find good videos on how they work.

From time to time, a little “hands-on” training is required. Over the years we have purchased several different junk-yard transmissions and torn them down, looking to see how they work and where the metals we see might be coming from.

Dissections like this tend to be a lot of fun and we learn quite a bit from the process. They are also low-stress affairs because we don’t have to worry about putting anything back together.

One of the first transmissions we took apart was a classic GM Turbo-Hydramatic, which was used in GM cars and trucks from the 1960s to 1990s (see Figure 1). It was always a bit of a mystery as to where lead came from in that type of transmission and it turns out, it’s a bearing metal, just like what used to be common in engines.

Nowadays, aluminum is the bearing metal of choice for most engines and transmissions, and that makes our lives a little harder when writing reports because aluminum can be from other areas too.

Shaking up the world of transmission oil

For years and years, automatic transmissions like this didn’t have any special oil requirements. They all pretty much ran on Mercon/Dexron ATF (automatic transmission fluid). This is a light oil (normally 10W) containing only a little boron, calcium, and phosphorus as additive. It was also traditionally dyed red, so when it started leaking you knew where it was from.

Then in the early ’90s, Chrysler came out with ATF+3 and this shook everything up in the transmission world. This oil is still a 10W in viscosity and still has a red dye, but the oil additives were significantly different than anything we’d seen before (or since) — see Figure 2.

This oil and the transmissions they were used in worked just fine; problems only came about when a different type of ATF was added by mistake. This caused the transmission to burn up because the new oil’s additive package wasn’t correct. We started getting a lot of calls about this type of transmission where the mechanic thought someone added engine oil to it, but it was actually ATF that had just turned brown due to excess heat. So this problem has been around for a while, but for the longest time it was limited to Chrysler products — until CVT transmissions hit the market.

CVT transmission & oil

This type of transmission is also known as a shiftless transmission and is similar to what you might find on a snowmobile. It has a steel belt connecting two sets of cones. Both cones can change their diameter, which essentially allows the unit to have an infinite amount of “gear ratios” available.

We dissected one of these a few years back (see Figure 3) to see what made them tick. These units tend to work well but are extremely sensitive to the oil they use.

Again, most of these oils are light in viscosity (10W) but they have a unique additive package, and they also tend to be dyed blue or green to differentiate them from the typical red ATF that many transmissions run. Unfortunately, we see a lot of samples from CVT transmissions where the wrong oil has been used. This causes the units to burn up because the belt driving the cones relies on the oil’s additives to maintain the correct friction.

“Lifetime” transmission oil

The early 2000s brought about the rise of “lifetime” transmission fluids and also sparked a lot of debate about what that meant and how it could even be possible.

The idea that there is a fluid in your vehicle that never needs to be changed goes again some people’s religion, and I’ll admit it was a little difficult to understand at first. My 2003 Volkswagen Passat had that type of transmission, and it didn’t even have a dipstick, so I couldn’t run any tests on it to verify that the fluid was in good condition. Still, the lifetime of that transmission for me was 91,000 miles (that’s when I sold the car) and I will admit I never had any problem with it.

Still, it just seems wrong not to change the transmission fluid every now and then. Up until that point, I had always changed the transmission fluid in my cars and trucks, but after a lot of thought on the subject, I’m starting to wonder if that’s really necessary. For a lot of vehicles, changing the transmission oil could cause more problems than it could help, due to the possibility of the wrong oil being used to refill it.

Also, it’s quite possible that the wear accumulation in transmission oil doesn’t have the same abrasive affect that it does in engines. To demonstrate this, I’d like to show you the first sample from my 1984 Chevy Custom Deluxe K20 pickup truck (see Figure 4). You might remember this truck from such classic newsletters as “Rebuilding a GM 350”, “ZDDWhat?”, and “The Renuzit Experiment.”

When I first bought this truck in 1999, I took a sample from the transmission and was sickened by the amount of metal that was present (see B30211). I immediately changed the oil several times myself and then got in the habit of having a shop change it every year or so. Still I expected that thing to give up the ghost at any moment and just hoped I wasn’t far out of town when it happened. The funny things is, it’s still running to this very day (and is still going as of June 2024).

Now maybe all of the oil changes that I did early on made that possible, but at this point I’m leaning towards another explanation: transmissions can make a lot of metal and still be perfectly normal.

I think that’s because the oil in transmissions has a significantly different life than engine oil does. Transmission oils are mainly used as a hydraulic fluid to shift the gears though an ingenious invention called the valve body. This is like a circuit board that uses oil rather than electricity, and apparently the cleanliness of the oil doesn’t affect its operation.

Sure the oil also lubricates the gears, but as far as an oil’s jobs go, that’s one of the easiest things for it to do. The oil really doesn’t even have to be very clean to do that job well. So if the cleanliness of the oil isn’t that critical, then lifetime transmission oils start to make sense.

The transmission killer extraordinaire

It has been our experience that what kills most transmissions is heat. If the oil gets too hot it actually loses its viscosity and is no longer able to lubricate properly, which in turn causes more heat and eventually a total failure.

So in closing, if you have a “lifetime transmission oil,” rest easy — there is probably no need to worry about changing it. You’ll likely get sick of looking at the vehicle before the tranny dies. However, if you notice your transmission starting to leak oil, that’s the time you’ll want to have it fixed because its lifetime will quickly expire if you don’t. Just be sure they put the right oil back in!

By Ryan Stark|2024-09-19T09:41:04-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

Fuel in Diesels

For our last newsletter, we did an experiment where we actually tried to get fuel dilution to show up in the oil. Amanda’s Kia was our guinea pig, and she tried hard to get some fuel to show up but had very little success. She tried idling for ten minutes and she tried lots of city driving, but could hardly get anything more than a trace or so. Maybe that’s just a testament to Kia and their fuel system engineering, or maybe she was just unlucky. It’s hard to say. However, fuel dilution does show up for a lot of our customers and after the last newsletter, we received some e-mails asking for more information about fuel, especially in diesel engines with possible fuel dilution problems.

A little history

Diesel engines started showing up in pickup trucks back in the 1980s and while those engines didn’t particularly wear well, fuel dilution wasn’t really a big issue.

In the 1990s, these engines really started coming into their own. Wear metals improved and the oil changes started getting longer and longer. Ford started using the Navistar 7.3L Power Stroke and Dodge used the Cummins 6BT 5.9L, and both were excellent engines. They produced a lot of power and left very little metal in the oil to show for it.

GM used the Detroit Diesel 6.5L, and while that was a good engine and a lot of them are still on the road today, it tended to make a lot more metal than its competitors. It wasn’t until GM started the Isuzu 6.6L Duramax that it really had a world- class diesel that was every bit as good as what Ford and Dodge were using.

With this new generation of engines, we started seeing people run 5,000-mile oil changes regularly, where the old standard was just 3,000 miles. And oil changes have gotten longer and longer since.

These days it’s not uncommon at all to see those engines running 10,000 miles on the oil without any special oil filtration set-up. Of course, a lot of that is dictated by the type of use they see. This was also the carefree days before emission controls starting becoming mandatory.

For some of you, the words emission controls may make you turn away in disgust and I’ll admit, on my own truck engine (a gasoline powered GM 350), the emission controls haven’t gotten the attention the rest of the engine has. But really the idea isn’t really all that bad.

Piston powered aircraft engines don’t have any emission controls on them, but those engines are plagued by rust and corrosion because condensation from the air is allowed to enter through the breather. Modern gasoline and diesel engines don’t have that problem because their crankcases are sealed to the elements and that keeps corrosion to a bare minimum. It’s also one of the reasons you don’t really need to change your oil on a time basis anymore. We get a lot of questions about if an oil will last a year or not and the answer is almost always yes, because very little corrosion builds up on these engines.

Of course, gasoline-powered engines have had emission control systems on them since the 1970s and that means the engine designers have had a lot of time to get it right. When emission controls started appearing on diesel engines in 2005 and 2006, there were a lot of growing pains with that introduction. Couple that with the fact that competition brought about the need for more and more power, and now we started seeing changes in the oil samples, mainly at fuel dilution.

We first started seeing a lot of fuel when Navistar came out with the 6.0L Power Stroke in 2003. Those engines almost always had a lot of fuel in the oil, especially when they were new¾and when I talk about a lot, I mean 4% and 5%.

We weren’t sure exactly what cased this, but it was showing up in almost every sample we saw and this presented a problem for us because we had always considered 2.0% to be an “action” level of fuel. So what do you do when every engine starts showing more than 2.0% fuel? Do you start sending every owner back to the dealer saying there’s a problem? And what do you do if you see a lot of fuel dilution, but wear metals continue to look good?

So the 6.0L Power Stroke caused us to take a different look at fuel and how much of a concern it really is. No longer could we consider 2.0% is a major problem. Now we suggest that it’s only an issue if the oil level is rising on your dipstick, or if the amount of fuel we find in each sample is increasing. As it turns out, continual fuel dilution in the oil at around 2.0% to 3.0% sometimes is from a problem, but it should not be considered a major one and I know about that first-hand.

About my Passat

In 2004 my wife and I bought a Volkswagen Passat with the 1.8L turbo gasoline engine. Almost from the start, this engine was leaving a lot of fuel in the oil and I would look at the analysis results and just shrug my shoulders. The engine was running fine and wear metals were acceptable, but the fuel mileage was never quite a good as advertised. For me, that didn’t seem like a good enough reason to tear into the fuel system.

Shortly after we bought the Passat, Volkswagen set us a letter saying they would extend the engine warranty to 10 years or 100,000 miles due to sludging problems they were having. I suspected these problems stemmed from a lot of fuel dilution in the oil coupled with really long oil runs, but I’m not sure. The kicker for the extend warranty was I had to change oil every 5,000 miles and I had to use a VW-approved oil. Of course, they approved expensive oils like Elf and Total, and those aren’t on my approved list. My list includes oils that are on sale at Wal-Mart, so I decided to stick with my oils and just change the oil at 3,000 miles. So far the plan has worked but if it fails, I’ll be writing about how I rebuilt the engine myself (twice) in my Dad’s barn.

In the end, we haven’t done anything about the continual fuel in our Passat’s oil (except curse VW), but the engine is still running fine and is close to the magic 100,000-mile mark. When we hit 100K, we’ll unload it and get my wife the new car of her dreams (a white Jaguar S-type). So despite the fuel being present in every report, really the only problem this has caused is our MPG isn’t quite what it should be.

Back to diesel engines

So anyway, the fuel dilution problems in the 6.0L Power Stroke eventually got better and those engines now look as good as any we see, so they’ve changed something to solve the fuel problem.

Then came the next generation of diesels (the 6.4L Power Stroke) and the fuel problems started up again. It’s not uncommon to sees excess fuel in over 2% of the small diesel engine samples we see today, and when it shows up that often, it’s hard to say it’s a major issue. It shouldn’t really be there, but it doesn’t necessarily warrant a trip to the dealer either.

The source of the fuel dilution differs from one engine manufacturer to the next, though injectors and emission control systems appear to be the root cause of most of these problems.

For the new 6.4L Power Strokes, if it’s not an injector it could be another part of the fuel system, like a pump. The DPF (diesel particulate filter) regeneration process will also cause fuel to show up in the oil. Does that mean these new engines are junk? Not at all. It just shows they have some growing pains to work out and once that happens, the fuel dilution problems will eventually taper off.

Until then, don’t get too excited 2.0% or more of fuel dilution, but do watch for an increased oil level on your dipstick. While you may think an engine that makes oil is like the goose that laid the golden egg, it’s really a possible sign of problems down the road. Small amounts of fuel are okay, but if the oil level is rising or if we’re seeing more and more fuel in each sample you do, fuel could be a problem.

By Ryan Stark|2026-01-19T14:26:18-05:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

The eBay Oils (Part 2)

Welcome back to the eBay oils! If you missed the first installment of this article, you can read it here.

True to his word, Ryan listened to his Passat (if you’ll recall, it was making a noise that sounded like “Sell Me” in German) and got his wife a new Hyundai Elantra this month. Free oil changes were not included as part of the deal, so Ryan will be changing his Elantra’s oil himself. And while he’s willing to experiment with his 1984 ½ ton Chevy pickup truck, it’s doubtful (for now, at least), that he’ll be using either Wolf’s Head or Fox Head oil in his new car.

Wolf’s Head SD 10W/40

Wolf’s Head Motor Oil Company was originally founded in Pennsylvania in 1879 as “Pennsylvania Crude.” (The source of this is Wikipedia, so take this information with a grain of salt.) I’d place the can from the late-1970s or early 1980s. It is “Formulated from Finest Quality Base Stocks and Superior Motor Oil Additives” and back then, like today, the container gives no actual clue as to what the additives are. That’s where we come in. The report is an interesting one. Note the lack of calcium, which is used in almost all engine oils nowadays as a detergent/dispersant additive. Instead of calcium, it contains a lot of copper as an additive. This is a trend we were glad to see die. All that copper in the oil masks bronze wear.

Wolf’s Head ATF

Wolf’s Head also made (makes?) an ATF, though the only selling point on this can is that it’s “Refinery Sealed.” Maybe they couldn’t think of anything interesting to say about it, because honestly it looks just like a lot of ATFs we see today: mostly phosphorus and zinc, with a smattering of other additives thrown in for good measure.

Fox Head 40W

Oil marketing has come a long way since the days of yore. Today when you want to buy a high-dollar oil you’ll find it has a name that conjures up something special: speed (Red Line), richness (Royal Purple), slickness (Amsoil), racing (Mobil 1), space-age (Quantum Blue), etc. I’m not sure what “Elf” is meant to conjure up, but they follow it up with “Excellium” so you know it’s Excellent oil. Contrast those names with our next contender, Fox Head, which just makes me think of…well, a fox head. In my oil. Fortunately, that’s not what analysis turned up. (Although…we don’t test specifically for fox heads, so we could be missing something here.) The Fox Head can is red, white, and blue, so you can feel patriotic when you buy it (unless you’re in Canada. Then you can indulge in justified rage about Americans and how we think we’re the center of the world). Fox Head oil was made by the Tritex Petroleum company out of Brooklyn, NY, and my extensive research (aka first-page Google results) tells me the company still exists and is presently located in Tulsa, Oklahoma. The logo, a sly-looking fox, has nothing on today’s slick oil packages. And the oil itself also has nothing on today’s oils: the oil itself is nearly bereft of additives. Basically a mineral oil, it has a little magnesium, phosphorus, and zinc in it, and not a lot else (Figure 3). This is not necessarily a problem, however. As you’ll recall in the article when Ryan used 30W aircraft oil in his truck, wear went up a little but the engine didn’t fail or anything. Still, I won’t be putting it in my Outback anytime soon.

Shell Rotella S 10W

Shell Rotella has been around for a long time. It’s good oil, and since they’ve been making it for decades, they’ve pretty much got the routine down and haven’t messed with it a lot over the years. Unlike now, when you can actually follow Shell Rotella on Twitter (who knew Rotella had so much to say?), back in the day Rotella had to get by just by on traditional advertising and word of mouth. We called Shell to see how long they’ve been making this oil and the guy not only could not tell me, but he was unable to tell me who might know. Surely someone at that company has a historical file? If so, they’re not sharing that info with plebeians like us. He did mention that Rotella really made its name in the ’70s, though I’m guessing this can of SF, SE, SC oil was made in the late ’80s. He also said the “S” versions of Rotella were sold internationally, and indeed, this can came from our friendly neighbors to the north (*waves hi to Canada). Suffice it to say that the oil has changed very little over the years. Its main additives are the same as what we see today, but the interesting part of this oil is that it’s a 10W (Figure 4). We often see heavy-duty thin-grade additive packages in tractor-hydraulic fluids, which are used in systems like transmissions and hydraulic systems in off-highway equipment like bulldozers and backhoes. Note the TBN of this oil read higher than most of the others we’re talking about. That’s because of the high calcium level¾the TBN is based on the level of calcium sulfinate and/or magnesium sulfinate. When those compounds aren’t present, you get a low TBN.

Quaker State 30W & 10W

Next up is another oil familiar to today’s buyers: Quaker State. This HDX oil is a straight 30W, and Quaker State was ahead of the marketing game on this one. The can’s copy touts their “high quality,” “modern refineries,” and “quality control laboratories,” and this was about as scientific as it got 30 or 40 years ago. The additive package is fairly stout, though like Wolf’s Head oil, calcium is in short supply (Figure 5). We also bought a can of Quaker State 10W oil, and when we looked at the report we had to go back and double-check the can to make sure this wasn’t actually ATF. It’s not: it’s labeled as an SAE 10W oil, though the additive package looks an awful lot like what we see of out today’s transmission oil. Interestingly, there’s a lot of barium in it (Figure 6). Barium must be expensive, or else it doesn’t do much, because we rarely see it in oil samples of any type nowadays. This is engine oil, but it might work in transmissions too.

Quaker State Deluxe 10W/40 & Sterling 10W/40

Apparently we are fans of Quaker State, because we also tested a couple more varieties: Quaker State Deluxe, and Quaker State Sterling. As you know, modern oil companies generally have a lot of different brands under the same name (for example, Valvoline has TK, TK, and TK, as well as TK). For the most part, these oils are mostly the same; they’ll throw in a few slight differences in additives and call it good. These cans of Quaker State, however, were mostly pretty different. The Deluxe version looked a lot like their 30W oil (but more calcium–Figure 7). Quaker State Sterling HD 10W/40, on the other hand, went out on a limb with almost 800 ppm sodium, almost no magnesium, and then levels of calcium, phosphorus, and zinc that are comparable with today’s oils. Touted as “Energy Saving Motor Oil,” Quaker State was getting its game on in pushing this brand: it mentions “special friction modifying additives,” the longevity of the company (over 60 years when the can was made), and its suitability for those wishing to follow extended drain intervals. Heck, I’m sold, and I see this stuff all the time.

Mobil Special 10W/30 & Artic 20-20W

Mobil is no slouch in the marketing department, but they really outdid themselves with the can we tested, “Mobil Special.” The name alone tells you all you need to know about why to buy this oil. All oil companies like to mess with their additive packages, and Mobil, like the others, changes their oil up fairly frequently. That was the case back in the day too, because the additive package in this “Special” oil is different from what we typically see in today’s oil. Apparently Mobil was an early rider on the ZDDP train, because this oil is chock-full of both phosphorus and zinc. Calcium and magnesium are present too, but at lower levels (Figure 8). We also tested a sample of Mobil Artic oil. The Artic can is clearly older than the other Mobil can¾the logo is older, and there’s no zip code listed with the address, so it’s pre-1963. A straight 20W, it’s labeled as HD oil, meeting “Car Builders’ Most Severe Service Tests.” While it’s “Artic” and not “Arctic,” we can’t help thinking this oil is meant for cold-weather operation. The can even looks like it’s ready for winter: all white, but with a little color on it so you don’t lose it in the snow when you’re out in the tundra changing your oil. This one definitely has an unusual additive package, relying heavily on barium (maybe it’s got a purpose after all!). Interestingly, less zinc is present than phosphorus (Figure 9). Nowadays it’s the other way around.

Phillips 66 Trop-Artic 10W/40

We were going to stop with Mobil Artic, but we can’t resist comparing that one with Phillips Trop-Artic. We’re not exactly sure what Trop-Artic means, but since the can is selling itself as All-Season we’re guessing it’s something along the lines of “use it in the tropics, use it in the arctic.” A 10W/40 in viscosity, this oil looks a lot like what we see out of modern 15W/40s¾a stout additive package and a relatively thick viscosity (Figure 10). In other words, even though this oil is several decades old, it would be fine to use in your F150 tomorrow.

Okay, ten old oils is all we can do for this article. Fortunately the next installment will contain such gems as old versions of Amsoil, Castro, Sinclair, Amoco, Lucky Strike, Union 76, and more! Tune in next time for the next installment of the eBay oils!

By Ryan Stark|2026-01-19T14:26:31-05:00July 20, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

The eBay Oils (Part 1)

We were visiting my in–laws last November and needed some oil for my Passat. It just starting to clatter a little on start up and when I checked the oil, it was down two quarts. The clatter sounded something like “Sell Me” in German.

Anyway, while searching for some make up oil (my father-in-law Lee had two quarts of my favorite—Super Tech), I came across an old can of Pennzoil ATF. By old I mean it was a round can made of cardboard, like a Crisco can. It brought back memories of helping my Dad change oil when I was seven or eight. (My job was jabbing the pour spout into the top of the can.)

Lee said he bought it for an old 1984 Buick LeSabre. That was the last car he owned that leaked oil and when that car was gone, he was left with half a can of ATF. Working in an oil lab, I was intrigued by what was in it. So Lee let me have the quart because he would never need it again.

When I got back home, I started looking at old cans of oil on eBay and found a lot. It turns out these are fairly collectable, and I found roughly 300 unopened cans for sale, of all different types and years. I decided that in the interest of science, Blackstone should buy some of these and test them to see what was in them.

Now, you may think I’m crazy because once you open an old can of oil like that you ruin the value of it, but I was prepared to make this sacrifice for the good of the oil analysis community, and plus, Blackstone was buying, so it really didn’t bother me too much. If you think about it, how lucky can you get to be able to buy little time capsules of a product and test it? Can you by beer from 30 years ago and still drink it? I guess, but chances are it’s long gone bad. How about a 30-year-old can of sardines, or a 5-year-old one for that matter? No way. So, I would really be a fool not to try this and see what shows up.

One thing led to another and before I knew it I had bought 28 cans of old oil and spent almost $1,000. Pretty soon these oils started rolling in and I experienced a little buyers remorse. Did I really need to buy all this? What was I going to do with the cans? Once you open a can of oil, it’s almost impossible to seal up properly. Would there be anything to even see in these samples? And, does oil go bad? We get this last question all the time, and my answer has always been no, but I was dealing with oils from the 1930s,1940s, and 1950s here–really old stuff. Maybe all the additive in there (if any was even used) would settle out and there wouldn’t be anything for us to read. Fortunately, I had bought some oil that would help answer that.

Shaken, not stirred

Before I did any testing, I wanted to see if I would need to shake these oils up. If the additive had fallen out of suspension, then all of these old cans would need to be shaken before I even opened them. Ideally, it would be great to have two oils of the same batch, so I could run one unshaken and run one shaken and see what type of difference shows up. That’s where my two antique vintage Havoline Texaco all-metal cans came into play. “SAE 20-20W” is stamped on the top of the can, and the text on the back says, “For API engine service classifications MM, MS, DG, and DM.” It also assured me that it’s “The finest engine protection in the world.”

I bought these two for $25.00 total, and going by what looks like a date on the can, I think they were from 1968. They were from the same seller and looked exactly the same. Chances are good they came from the same case someone bought years ago and they have been sitting on the shelf even since.

I decided to run a test. I would take one to the local hardware store (www.doitbest.com) and have them put it in the paint shaker for five minutes. Then I would crack them both open, test them, and see what differences showed up. You can see the results in Hav No Shake and Hav Shake.

To my surprise, there was actually more of some additive in the oil that I didn’t have shaken. Also, the additives really weren’t that different from what we see in today’s oil. The oil was supposed to be a straight 20W and it was. Also, it had a strong TBN, so the additive that was present was still active.

About the only unusual thing was that phosphorus was higher than zinc. Those two elements are normally from the ZDDP additive, but maybe there were using a different formula back in 1968. It’s hard to say, but from that test I learned that when it’s done right, the additives actually become part of the oil during blending and time/gravity alone won’t cause them to separate back out.

So that settled it. I didn’t need to shake all of these oils and could just start running them. That’s good because some of these old cans were bound to break open during shaking and spray oil all over Norm and his paint department.

But is it still good?

However, that really didn’t get down to answering the question: Is this oil still good to use? For that, I was going to have to run another test.

Of all the oils I bought, one of the most expensive was very rare—according to the seller, antique Renuzit Certified, Premium Quality 2500 Mile oil. Not only does this oil offer the ability to run the oil 2500 miles in between oil changes (“Cut your oil bills in half!”), but it claims to provide a longer engine life, smoother motor, stronger oil film, and best of all, “a faster getaway.” They don’t actually advertise it as the best oil for bank robbers, but they should have.

It cost $75.00 + $25.00 shipping, but I got a whole gallon of it. Unfortunately, the can had some rust on the bottom of it and it started leaking during shipping. The good news was, I now needed to do something with this oil and I wasn’t going to dump it in a waste barrel. So I am going to actually run this in my engine. Not in my Mini (it’s still under warranty), but my trusty old GM 350, rebuilt twice by yours truly.

I know what you are thinking—this SOB is out of his mind!—but don’t try to talk me out of it. I’m going to run this oil and decide once and for all if running old oil really hurts anything. Will my engine blow-by and leave me stranded on the side of the road? Will the seals start leaking like mad a leave a slick of oil behind for other cars to slip on and spin off into the ditch (a la Spy Hunter)? Will this be the end of my beloved 1984 Chevy Custom Deluxe? Well, like the monkey said after he shit in the corner—that remains to be seen!*

Castrol with Tungsten

My first purchase was Castrol with Tungsten. Tungsten! What the hell? Since when did they start putting light bulb filaments in oil? Or maybe a better question would be, “When did they stop?” The bottle was partly in French, so I’m guessing it was from Canada, and that makes sense; the oil blenders up there will put anything in the oil and if the engine breaks, they just blame it on the cold. (Just kidding, Canadians! You know we love you guys.) I had to buy the single element standard to run Tungsten and set our spectrometer to run it, but after a little messing around, we got some results .

Sunoco DX Diamond motor oil – API SB

After seeing Castrol with Tungsten, I was ready for anything, but when I saw Sunoco’s Diamond oil, I didn’t really think they put diamonds in there. That would be one expensive additive. I did want to see what was in this SAE 40W oil though.

The case says is has an API rating of SB, which was used from 1930 to 1963. Several websites state that this oil can cause equipment harm. All I can say to that is, too bad I don’t have five quarts of this stuff, because I love a challenge. It doesn’t look so harmful in the oil analysis. The viscosity wasn’t quite in the 40W range and it didn’t have much in the way of detergent/dispersant additive present, but then again, it does state on the can that it is “Recommended for vehicles that do not require detergent oil.” Sometimes those oils don’t have any additive at all, but there was quite a bit of phosphorus and zinc here (figure 4).

K-Mart 10W/40 Motor Oil (API SE) & DEXRON ATF

Back before Wal-Mart dominated the world, there was K-mart, and when I was in 4^th grade, there was no greater crack on someone than “You buy your underwear at K-Mart.”

Well, I wonder what those boys would say if they found out I bought my oil at K-Mart too. The motor oil is listed as Deluxe and it says on the side of the can that this is specially blended multi-viscosity oil containing the finest approved additives and base oils. So you can’t go wrong there, right?

Looking at the results, I’d say this oil is indeed deluxe. The viscosity is pretty strong for a 10W/40, and the additives would be suitable for diesel use. The oil does have a CC rating as well as an SE rating, and those put the date of this oil as being made sometime in the 1970s. The ATF has a standard additive package until you get down to barium. That’s not used much anymore. See figures 5 and 6 for the analyses.

Valvoline SAE 20W – API SB

The big marketing claim for this oil says it “Contains Miracle ChemAloy.” Miracle! Really! Does the Pope know about this? There were no miracles in the additive package that I can see, but maybe that’s the miracle of it—you can’t see it, but it’s in there and it works. This oil doesn’t have much of a TBN because it doesn’t contain much calcium, but the old stand-bys of phosphorus and zinc are there, and at pretty much the same levels we see today (figure 7).

Harley-Davidson Premium Grade Motorcycle Oil (SAE 40) 75-P

This can caught my eye because it reminded me of Evel Knievel. In fact, the logo on the can is the same as what is on Evel’s website, so the two were heavily linked back in 1970s.

What’s interesting is that Harley-Davidson actually came up with their own oil weight specifications. This can is 75 Medium Heavy and is for use in all motors at temperatures above 40°F. They also made 58 Special Light, which is good for temperatures below 40°F, and 105 Regular Heavy—good for all motors operating under severe conditions at high (?) temperatures. Apparently, it was up to us to decide what high temperatures are; also, neither the 75 or 105 was “special.” I’m sure the special label added some extra cost and that made it special to Harley-Davidson.

Looking at the report, you’ll see this was a 40W oil and WOW look at the barium. That isn’t used much anymore and was likely some sort of detergent additive (figure 8).

ARCO Graphite SAE 10W/40 (API SE-CC)

After seeing the word graphite in the name, I had to check this stuff out. True to its label, there was a lot of graphite in the oil (figure 9), and if you’re the kind of person who likes clean oil on your dipstick, this wasn’t the brand for you. Graphite is known as a lubricant, but I wonder how this stuff did in engines. Looking at the report, you can see the graphite at the insoluble reading of 0.5%. That’s extremely high for virgin oil, so the stuff doesn’t stay in suspension very well. On the plus side, the can says this oil provides

Improved gasoline mileage
Reduced piston ring and cam wear
Easy low temperature starting and excellent lubrication at low and high operating temperatures

The oil is also “Patent Pending” and I’m wondering how that application is progressing down at the Patent office these days.

In Parts 2 and 3 of “The eBay Oils” we’ll be looking at old cans of Amsoil, Mobil, Valvoline, and more. Look for the next installments this summer!

By Ryan Stark|2026-01-19T14:26:49-05:00July 19, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

Ryan’s Cholesterol

A few years ago I went to our family doctor for a checkup. For most of my life I’d never been one for getting check-ups, but now my insurance company pays for a yearly visit, so I decided to start.

After all the basics, the doctor suggested I do a blood test, because I’m “getting old” (almost 40!?). So after fasting for 24 hours to make sure nothing I ate would skew the results, I headed to their lab to get my blood drawn.

You can imagine my dismay when the nurse called a few days later with my test results — high cholesterol! My initial reaction was shock, followed by a realization that maybe I am indeed getting older.

The nurse said my total cholesterol read 203 and that the doctor wanted me to change my diet and start taking the drug Lipitor. Again, more shock followed by a little confusion as to what exactly 203 meant, and then a wave of depression at the idea of having to take a drug for the rest of my life, along with quitting eggs, butter, and bacon. “Fortunately,” the nurse continued, they offer free Lipitor at the local supermarket pharmacy, like that was supposed to make everything all better.

After a few letting this all sink in, I decided that I was not indeed getting older. In fact, I’d wager that I was the healthiest SOB my doctor had seen all month (based on the state of the patients in her waiting room).

Looking at data

Also, given the fact that I look at data all day long, I began to wonder about the 203 reading. What’s average, what are the units on that, and what was my average cholesterol reading? Maybe I’ve always read high.

After a little more thought, I decided to just ignore my doctor and get retested to see if I can get a trend going. My thinking was, maybe high cholesterol is kind of like high iron in your oil. We normally say that just one high reading isn’t much of a concern. Maybe it was higher before but it’s headed down now, or maybe this level is just normal for you and the way you operate your engine. A trend gives you far more information that just one bad reading. We usually wouldn’t suggest any major changes after one just one high reading, so I was a little disheartened that my doctor would prescribe a lot of life-changing measures based on one test. My course of action would be to get more information about it and check back to see if the high reading was a one-time occurrence or not.

So I had my blood tested again about a month later to see if the first test was accurate. Unfortunately it was, but still, that made me feel a little better about the repeatability of the lab and that test itself.

The vitamin D cure

As luck would have it, that same month I attended a lab training session in Columbus, Ohio at Mettler Toledo (they make an awesome auto-titrator if you’re even in need).

During dinner one night with the other class attendees, we got to talking about Vitamin D and its relationship to cholesterol. My classmate was in the business of testing for Vitamin D levels in food and said that there is a direct relationship between the two. As it turns out, the more Vitamin D you get, the lower your cholesterol goes. And what’s more, Vitamin D is free to us all, being produced naturally by your skin when it’s exposed to sunlight.

This really got me thinking — my first and second blood tests were taken in during the high of winter in the Midwest. A person doesn’t get much sunlight in the winter (at least in Indiana). So maybe if I checked my cholesterol again in summer, it would improve. This started me on a quest to get my blood tested again that summer to see if I could indeed confirm that there was a relationship between Vitamin D and cholesterol.

At the start of September, I called my doctor and requested another blood test, and this time I wanted Vitamin D added as well. After a few days the nurse called with my results. It turns out my Vitamin D level was low at 30, and she wanted me to start taking a supplement to see if I can bring that up (again with the knee-jerk reaction to one reading).

“How about my total cholesterol?” I asked. “Oh, that’s fine at 156.” she stated. This was an eye-opening test because it proved that my cholesterol level did indeed change significantly and I didn’t have to change my diet or take any drugs to artificially lower it.

This also brought up a mildly chilling realization. Suppose I started taking a drug to lower my cholesterol back in February and then had it tested again in September. My cholesterol would have read lower, but everyone would have pointed to the drug as the reason and I’d be stuck taking it for life.

After-market oil additives are a parallel to this in the oil analysis world. A lot of people start to use an additive and after several years start to think it’s the reason their engine is running well. When in reality, chances are very good the engine would still be running fine had they not used the additive.

Trends are key

All of this started back in 2013 and I have accumulated a lot of data since then on my cholesterol and Vitamin D levels. Being in the lab business, I wanted more data before I made any hard and fast statements and I’m still not ready to say one way or the other that the Vitamin D and cholesterol are related. I’m not advocating that you ignore your doctor’s advice (that’s a Stark family virtue), but I am saying that as far as testing goes, it’s not very often that you need to take action just on one bad reading. Trends are important when analyzing data, so be sure to get them even if it takes a little pain.

By the way, during all of this blood testing, I found myself longing for a lab where you could walk in and easily get blood work done without a doctor’s order, one that would send you your results in a nice, easy-to-read format, with an explanation of the data in plain English.

Also, the report would show you an average so you could get an idea about how high or low a reading might be. Whoever could come up with this type of medical lab in real life would be sitting on a gold mine. Now, you may ask, “Why don’t you start one, Blackstone?” and the answer to that is easy—we’re too busy testing your oil.

_______________________

Cholesterol follow-up

Back in August 2015 I wrote about cholesterol testing and its parallels to oil analysis. I’m sure you’re all wondering how my health has been, so this is a follow up to that. In the article I stated that there appears to be a connection between Vitamin D and cholesterol and I am here to tell you that I might have been wrong.

My final blood test was on August 7, 2015 and at the time I was taking a Vitamin D supplement to see if it would lower my cholesterol. Well, the supplement worked: my Vitamin D increased to 33, which was an all-time high; however my cholesterol also increased. So barring any sort of lab error that might have occurred, I’m not sure if there is a conclusion or not.

That article received a lot of feedback and I enjoyed all of the comments from our customers, but was especially intrigued by one e-mail I received. He pointed me towards the book “The Great Cholesterol Con,” by Malcolm Kendrick, and while it wasn’t the easiest read I’ve ever come across, it did change my life.

The books states that cholesterol levels aren’t related to heart disease at all and that I should eat anything I like. Well, I’m 43 now and can make up my mind on what I do, and I have to say, I really liked the sound of that. It was the first time I had ever heard anyone say that your diet isn’t related to heart disease and he had that data in his book to back it up.

I’ll admit I never read any of the studies he talked about, though apparently they are all available on the Internet. As for what causes heart disease, well, I won’t spoil the book for you ¾ ha ha just kidding, I’ll spoil it: stress! Reduce that in your life and you’ll be better off. Who can argue with that? Plus now that I don’t have to feel bad about putting butter on my toast, my life just got less stressful.

_______________________

Yet another follow-up

A few years ago I wrote an article about how trends in blood tests were just as important as trends in oil analysis. This medical talk spurred a lot of comments and advice which I greatly appreciate, though surprisingly enough, not too many of you seemed concerned about my suicidal-scorn for statin drugs. Still, I’d like to thank all of those was responded and I’d like to pass on one bit of great advice from a doctor/pilot. His best advice for living a long healthy life: Stay off ladders.

By Ryan Stark|2024-09-19T10:15:06-04:00July 19, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

Aircraft Problems: Should I Be Worried?

One of the main purposes of oil analysis it to find problems that might be developing in an engine, and after doing this for a lot of years, I can say without a doubt that it works. However, some problems are more urgent than others, and part of our job is to determine if a problem is a major one or not. Most engine problems start out minor but if left unchecked can lead to major issues, which eventually result in an engine’s demise.

Minor problems

Abrasive Contamination

Dirt getting past the air filter will cause a lot of problems in an engine, and piston scuffing is the primary concern. Fortunately, most air filters do a really good job even when they are dirty. If you change your air filter on a regular basis, then this type of problem is pretty easy to avoid, but remember, it’s also important to check the whole air induction system down-stream of the air filter to make sure no cracks or other problems exist that could be letting dirt in.

Fuel dilution

This generally includes any fuel level between 1.0% and 3.0% that keeps showing up again and again. This is not a normal situation, but it doesn’t necessarily cause an engine problems in the short term. Still, since fuel is a contaminant, it will cause the oil to oxidize faster that it normally would. That typically causes problems like stuck oil control rings, which leads us to our next minor issue.

Oil Consumption

This one isn’t really a problem at low levels because all engines are designed to use some oil. What you really want to watch out for is a change in how much oil is being burned. If you always use 1 quart every 10 hours and it suddenly jumps to 1 quart every 3 hours, then you know something has changed. That’s part of the reason we ask about oil added between changes. If you’re not losing oil due to a leak, it’s either getting past the rings or the valve guides. Granted, you can buy a lot of make-up oil for the cost of a top overhaul, but there will probably come a time you’ll have to bite the bullet and fix the issue.

Corrosion

If you fly around 5 hours per month, that should keep this minor problem off you mind, though we all know that life doesn’t necessarily allow this. Still, if corrosion is minor it should easily disappear once the engine is back to flying regularly. If corrosion gets so bad that it causes pitting on the parts, that’s when the problem elevates to major status.

Major problems

Cam spalling

This one is often directly related to corrosion getting out of hand, though it can also be related to oil starvation on things like cold starts and high RMP starts. It takes time for that thick oil to get circulating through the engine and if it doesn’t get to the cam and followers fast enough, metal-to-metal contact happens. Problems of this nature won’t necessarily cause an engine to fail, but can lead to loss of some power, which might be needed to clear that 50’ obstacle at the end of the runway.

Excess Heat

This is really a pretty broad category and is often due to operational factors, though it’s almost always avoidable if you are paying attention to your cylinder head temperatures. If those are getting too hot, then maybe the cooling baffles aren’t quite working like they should. Maybe you have a crack in an air induction tube. That could allow abrasive dirt into the combustion chamber, but would also cause that one cylinder to run leaner than others (due to extra air being sucked in) and likely hotter. Excess heat causes the parts to expand more than they were designed for and that’s when wear starts getting heavy.

Stuck or Burned Valves

Abrasive contamination, fuel dilution, and oil consumption will all contribute to this type of problem. Sticking valves can be identified by things like morning sickness (not necessarily in the morning), intermittent rough running, and high mag drops (not due to a fouled spark plug). Burned valves are usually pretty easy to spot with a borescope though might not necessarily cause major operational problems until they burn to a point where compression has significantly degraded.

Detonation

This issue develops in an engine when the combustion process is not completed correctly, usually when an engine is under a heavy load and producing a lot of heat. It can easily burn a hole right through the top of a piston, resulting in all of the oil in your engine being pushed out the breather tube and oil starvation (see below). If your engine had a good muffler, you would hear a ticking or pinging noise, but since those don’t exist in general aviation, this problem can often go unnoticed without the help of oil analysis and/or engine monitor data. If this problem exists, running a richer fuel/air mixture to keep the engine cooler should help.

Instant failure

Oil starvation

Whether it’s caused by oil consumption left unchecked or severely worn bearings not letting oil get to all of the parts, this type of problem will cause an engine to fail in short order and it’s usually accompanied by the worst sound your engine can make — silence.

Spun bearings

When the babbit is worn off your bearings, either due to hard use, abrasive oil, or lack of oil, you will start to lose oil pressure. If the problem gets severe enough, the spinning shaft will actually weld to the bearing itself and spin in place. Once this happens, the engine is pretty much shot, though amazingly enough it might still run (but not for long).

Outside causes

Of course there are lots of other things that can cause instant engine death — see the first cartoon on this link for an example, or, although it’s not a plane, this picture of my flooded MINI. Unfortunately, outside factors probably take more engines down than anything else.

It’s pretty rare for engines to fail suddenly due to minor issues, so when we see something going on, that doesn’t necessarily mean you need to get out the wrenches or head straight to the engine builder and demand a repair. Usually, you’ll have some time to see if the problem persists or is getting worse. Once that has been established, then some action will likely be required to keep the engine going, but the cost should be minor compared to the hassle and expense of having to replace the whole engine. So test your oil every now and then. Chances are good your engine will look perfect, but if it doesn’t, you’re better off knowing about it sooner rather than later.

By Ryan Stark|2026-01-19T14:27:01-05:00July 18, 2023|Aircraft, Articles|Comments Off

How Often Should I Change My Oil?

When it comes to the questions we get here at the lab every day, right up there with “What kind of oil should I use?” is “How often should I change my oil?” Continental and Lycoming both have guidelines in place, and generally speaking it’s 50 hours for those with spin-on filters and 25 hours for engines equipped with oil screens. But as you know, way more than calendar time should go into determining how often you should be changing your oil. There’s not just one answer for everyone. The engine manufacturer’s guidelines are better than nothing, but there’s also oil analysis. Guess which method we like best for determining how often you should change the oil?

Inactivity

One of the biggest factors we use in determining how often to change your oil is how active the engine is. We used to say you need to fly ten hours a month to keep corrosion away, but a few years back we realized that people were doing fewer hours than that and still getting decent wear numbers. So we lowered our general threshold to five hours of flying a month as what we consider “active” for an aircraft engine.

The problem is, a lot of people don’t like to admit their beloved aircraft has been inactive. But it’s okay to admit it. We can almost always tell. We even have a little question on the back of the oil slip that says “Any inactivity or problems/suspicions?” Inevitably, someone will pen a big NO in that space when in reality, he or she let the plane sit for eight months, then flew it 10 hours in the span of a month. “No!” they protest. “It hasn’t been inactive! I flew 10 hours this month!”

Inactivity usually shows up as aluminum and iron, from oxides and wear at the pistons and cylinders, though other metals can show up too. Trust me, it’s okay to admit when your engine has been inactive. That’s generally an easier and more fun problem to have than a bona fide mechanical issue. When we suspect corrosion, we almost always recommend cutting back to a shorter oil change. While changing the oil more often doesn’t prevent corrosion from happening, it does allow you to 1) monitor the corrosion to make sure it’s not getting out of hand, and 2) get the metal-laden oil out of the system sooner, so not as much metal gets washed into the oil when you crank over the engine. Abrasive oil causes more wear. Even if you have to change the oil with just two or three hours on it, that’s fine. We’d much rather see that than a fill that sat a year, accumulated 20 hours, and was full of metal.

Metal

Of course, as an oil analysis lab we also look at how much metal your engine is producing. If you’ve seen our reports, you know that we keep a database of all the engines we’ve ever seen. We average their wear and then compare that to your own sample to see what’s reading high, what’s normal, and what’s better than most. We like it when you send along notes. The more you tell us about what’s been happening with the engine lately or any specific conditions that might affect the sample, the better our comments on your sample will be.

An engine that’s making more metal than average will usually need more frequent oil changes. That doesn’t fix a problem, if one exists, but it does help you to monitor it more closely and get the abrasive oil out of the system sooner rather than later.

Contaminants

The main contaminants in aircraft engine samples are fuel, water, and blow-by. Blow-by is hard to avoid ¾ all engines blow by to some extent. You want to see lead holding steady from sample to sample. If it’s increasing, we’ll often recommend shorter oil changes until you can figure out what’s going on.

Water can enter the system just from condensation in the air, though we don’t usually see more than a trace from that. And traces of moisture, while not ideal, probably aren’t going to hurt too much. They might accelerate corrosion if you’re not flying all that much, but usually a trace of moisture won’t cause too many problems. When more than a trace of water is showing up, and it’s showing up in every sample, it can be a sign of something else going on. Often, an incorrectly set-up air/oil separator will cause moisture in the oil. When we’re consistently seeing more water than normal, we’ll often recommend going to a shorter oil change.

Fuel is also a common find in aircraft samples. We recommend taking the sample hot to eliminate any normal traces of fuel and moisture, but sometimes people have to take a cold sample, which results in fuel. And that’s okay. As long as you tell us about it, we’ll take that into account when we write the comments and we probably would not recommend using a shorter oil change just for traces of fuel. You can also get fuel in the oil from excessive priming, and again, as long as it’s not showing up in every sample, this is usually something that does not affect wear and will clear up next time. If, however, we’re seeing a lot of fuel from sample to sample, it can be a sign of something else going on so we would likely recommend a shorter oil change until you can figure out what’s up.

Environment

Where you fly also affects how often you need to change your oil. Inactive engines in a dry place like Arizona can usually get away with keeping the oil in place longer than someone in Michigan or North Carolina. In fact, humidity can cause us to alter our standard less-than-5-hours-is-inactive rule. Someone in Georgia may be flying 8 to 10 hours a month and still getting signs of corrosion and need to change more often than someone with the same engine near a desert.

Acids

There’s a lot of talk out there about needing to change the oil more often due to acid build-up in the oil, and we’d say that’s a load of hogwash. In fact we did an article on that topic for our last newsletter. Basically we ran total acid tests on a whole slew of aircraft samples and only three out of 63 samples had a TAN (Total Acid Number) over 2.0. And 2.0 is still a low reading ¾ we consider anything above ~4.0 to be acidic. Never say never, but I predict pigs will be flying before we’ll tell you to change your aircraft oil because it’s getting too acidic.

What about the oil?

Notice what we have not said we take into account: the brand you’re using and whether it’s straight-weight or multi-grade oil. When Jim started this company back in 1985 he came up with a line he liked to use: Oil is oil. We still stand by that today. The oil guys would have you believe otherwise, but brand really does not seem to make a difference in how your engine wears, or how often you can change your oil.

Well, okay, if you’re using Joe Bob’s Oil that he “recycled” in the back of the hangar from emptied-out oil pans that he filtered with a piece of cheesecloth, we might say in that case brand does matter. But as long as you’re using an aircraft-certified aircraft oil, your engine probably isn’t going to care what you use. We like straight weights and we like multi-grade oils. In the end, what you use and how often you change your oil is completely your choice. We’ll give you our recommendation and you can do whatever you want with it. If you want to run longer on the oil despite having high wear, that’s totally fine. And if you have great numbers and you really like changing the oil often, we’re not going to send out the Blackstone henchmen to tell you to start running longer. Keep your own situation in mind and make your informed decision based on what’s showing up in the oil and filter/screen, what the engine monitors are telling you, and your own comfort level. It’s your airplane and your money!

By Ryan Stark|2026-01-19T14:27:14-05:00July 18, 2023|Aircraft, Articles|Comments Off

The Acidity Question

Every now and then you hear about oil becoming acidic and causing internal corrosion in an aircraft engine. Usually that goes along with the oil absorbing water and then forming acids, but I’ve always disagreed with this statement.

It’s a well-known fact that corrosion is a problem for a lot of aircraft engines that don’t see much use, but is it really acidic oil that’s causing the corrosion, or simply bare metal parts being exposed to the atmosphere? So I decided to run some testing to see what I could find about acidity and aircraft oils.

Now, think back to high school chemistry. Remember learning about acids and bases? Normally with something like water, you measure the pH to determine how acidic or basic a liquid might be. A pH of 7 is neutral, lower than 7 is acidic, while higher than 7 is basic.

The problem with oil is, you can’t run a pH on it directly. So instead, we have the Total Base Number (TBN) and Total Acid Number (TAN) tests.

These are fairly simple tests and the basic principle is this. After you mix a measured amount of oil with some chemicals, you can run a pH on those chemicals. But that doesn’t equate to the TBN or TAN.

To get the TBN you add acid to the chemical mixture until it reaches a pH of 4. To get the TAN, you add a base to the mixture (in this case, potassium hydroxide) until the pH reaches 10. (You might wonder why we don’t just report the pH of the chemical mixture and have that be the end of it, and the answer to that is unknown, at least to me.)

The TBN test

The TBN test is commonly done on automotive oils, but not aircraft oil. That’s because the TBN always reads 0 or close to it with aircraft oil.

Automotive oil has a lot of additive packed in there and that is what the TBN reading is based on. That additive makes the TBN increase. Oil salesmen use the TBN test to help sell their oil, with the idea being that the higher the TBN, the better the oil. But the TBN is really just a testament to how much additive the oil starts with, not necessarily how well the oil will work in any given engine.

You might wonder why aircraft oil doesn’t use the same additives? It’s because the additives used in automotive oils aren’t ashless. The additives present in all aircraft oils have to be ashless, meaning when the oil burns nothing is left. This is why it’s a bad idea to use anything other than aircraft oil in your aircraft engine.

The TAN test

The TAN test is commonly done on industrial oil like hydraulic fluid. There is a theory that when oil becomes acidic it will accelerate wear and cause all kinds of problems, but that’s just a theory — and a pretty weak one in my book.

When most people think of acid, they might think of something like acid reflux and heartburn. Or maybe sulfuric acid burning a hole in their clothes, but that gives acids a bad rap. If it weren’t for acid, your food wouldn’t get digested and we’d be without a lot of very important chemical compounds. What’s more, there is no known correlation between acidic oil and higher wear that I know of.

It is commonly talked about that water in oil will cause it to become acidic, and maybe it will if the water has something to react to. But with aircraft oil, it doesn’t. The additives present aren’t sulfur-based like they are with automotive oils, so when water gets into oil, it usually just stays there until the oil gets hot enough to cook it back out.

Testing the theory

So for this newsletter article, I decided to run some TAN tests on various aircraft oils and see what shows up. Virgin aircraft oils usually have a TAN in the range of 0.4 to 0.8. It’s important to know where the TAN starts out, so you know how acidic the oil has become after use. (You’d think that oil starts out with a TAN of 0.0, but usually it does not.)

For the used oil data, we tested the TAN on 63 random aircraft samples.

Acid Chart

The average TAN reading for those samples was 1.3. That might seem like a fairly large increase, but in the oil analysis world, 1.3 is considered a low acidity reading for any type of system. A reading of 3.0 shows some acidity and anything over 4.0 can be considered fairly acidic.

The highest TAN reading we found was 2.3, but in our testing any readings over 2.0 were rare. In fact, only three samples read higher than 2.0 and none of those had water present, but two were considered inactive. Five of the samples we tested did have a trace of water present, but their average TAN was just 1.1, so we didn’t find any correlation between water and a high TAN.

Acid Chart 2

So how about inactive engines? Two samples that were inactive did have a TAN of over 2.0, but they were the exception, not the rule. We had 11 samples in our test run that were considered inactive, but the average TAN of those was just 1.2.

Based on this testing, it doesn’t look like oil acidity is really a factor at all. Does that mean you shouldn’t worry about inactivity? No — we’ve seen too many examples of poor wear from inactive engines to say that’s not a problem. What it does mean is that in our opinion you don’t need to worry about your oil being acidic. And in life, one less thing to worry about is a good thing!

By Ryan Stark|2026-01-19T14:27:25-05:00July 18, 2023|Aircraft, Articles, Gas/Diesel Engine, Marine|Comments Off