Gas/Diesel Engine | Blackstone Laboratories

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|2026-06-05T16:16:51-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

A harrowing tale

It was a late and dark night in the California mountains. Our 36-foot, hinged-in-the-middle rig was straddled in a sharp “V” across a two-lane mountain highway, with no obvious way to get unstraddled. Behind us was a vertical rise in the terrain going straight up, in front of us a sheer drop off that appeared to be a black abyss. Up and down the highway the pavement curved to invisibility. We were sitting ducks for any unsuspecting semis that may have been motoring innocently along the route at highway speeds. I could imagine our stranded rig suddenly coming into view of a trucker who knew in a flash his goose was cooked: He could shoot off the cliff or T-bone us. It would be a spectacular crash.

How we got in this predicament is embarrassing. It was the fourth consecutive driving error on my part and it could have been my last. My truck was not ideal for towing: I had the off-road package, not the towing package. Gas stops in the California mountains are infrequent, making it nearly impossible to drive on the bottom half of the tank. We had planned to arrive on the west coast at 6:30 pm. But we needed gas, and no gas was available in the foreseeable future, so we had to turn around. We’d passed a Shell station 35 miles back and the only solution was to drive back and fill the tank.

We were quite tired by this point, and frustration was setting in. The drive back was up and down steep grades. When the station finally came into view we were coming down a steep grade and we saw the station on the right. What we missed was, the road curved sharply to the right and the station was actually on the left. This is important, as you’ll see.

After filling up, I ran over a tall curb getting back to the road. It wasn’t a huge problem, but the camper doesn’t have much ground clearance and the scraping noise was painful. I turned left to finish our drive to the coast. Kathy dozed in the right seat.

Maybe 45 minutes later, I started wondering where all the hilly terrain was that we had driven over getting back to the gas station. I woke Kathy and asked her to turn on the GPS. You can probably see where this is going, right? We were headed east, not west! The frustration level immediately increased to a silent roar inside my head.

I needed to turn around (again) but there were precious few places to do so. I finally found a wide spot in the pavement, just wide enough you could pull a car clear of the road. I pulled as close to the side of the mountain as I could and swung a hard left to make the u-turn. As we neared the far shoulder Kathy screamed, “STOP!” I raised up off my seat for a look and our right tire was about to drop off the side of the cliff, into the blackness.

What to do? I was already jack-knifed. I didn’t know if I could gain anything in reverse but I sure couldn’t go any further forward. After a moment’s consideration, I cranked hard right in reverse and forced the jack-knife as tight as I could without breaking anything. I cranked hard left, shifted to 1^st gear and popped the clutch. I’ll never know if that right front tire caught air or not, but we didn’t drop off the cliff.

We finally made our destination at 11:30 that night. We had to stop at the Shell station a second time to assure we would make it. All the rest of the drive I was thinking, don’t make a fifth error. It will surely be the end!

The trailer

We were pulling new camping trailer we had bought the week before we left. I had no experience towing loads other than incidental occasions in my 50-plus years of driving. A couple times unreasonable trailer loads had nearly overwhelmed whatever vehicle I had been driving at the time. This was experience I didn’t want to repeat.

We had been planning to drive to the west coast for some time, but only at the last moment did we realize we had the funds to buy a camper. Kathy used to own a trailer that she pulled with a half-ton pick-up. It was an older unit and heavier than what we eventually bought, a 16-foot unit that weighs just short of 3,000 pounds empty.

I drive a Toyota Tacoma and until I actually studied the owner’s manual about weights and capabilities (well into our towing trip), I had no idea the limits of my truck. I made the trailer purchase based on hitch weight, a number I looked up as we were talking to the camper salesman. He said we could pull this unit and I was little less than shocked to find he was right. The hitch weight of the trailer we were looking at was about 50 pounds less than the Toyota book suggested I could put on the hitch. With that fact alone, we went ahead and bought the trailer. The salesman said: “You won’t even know the trailer is on there!” How many times have you heard something like that?

The experiment

I wanted to leave my old oil in the crankcase to demonstrate how abrasive, used oil can affect the bearings when you work an engine hard. Toyota engines don’t make much metal under any circumstances, and for the near 100,000-miles I have driven this truck, I’ve never seen as much as 1 ppm lead in the oil from the bearings. Typically I change oil every 9,000 miles. Most of my driving is easy: country roads at moderate speeds, only rarely hauling anything, though I don’t hesitate to bump redline often…like nearly every time I drive. Don’t ask why. I’m out in the country and I just like the feel of the engine as it accelerates past 5,000 rpm. I’ve always contended that driving an engine hard doesn‘t hurt anything so long as you stay within redline. I’m still of that opinion.

Anyway, for this trip, I wanted to demonstrate that you can get poor bearing wear if you work an engine hard with dirty oil in it. I had more than 5,000 miles on the oil when I bought the trailer. Miles on the oil were accumulating fast and I still hadn’t left. I knew the next drive was going to be more than 6,000 miles…and at the last minute I chickened out. I could imagine the oil was going to be running warmer than usual and at 11,000 miles or so, the 5W/30 oil could turn to sludge and I’d puke the engine. I’d never live that down.

So I changed oil at the last minute and also had the rear differential and transmission serviced since I knew those gearboxes would run warmer as well. When I got back from the drive I knew I would have a nice apples-to-apples oil analysis comparison for the engine: the first analysis showing routine wear under no-load driving, the second I assumed would show much higher wear after abusing the engine to the extreme with a heavy load in mountains and across deserts.

Get up & go!

Kathy had a week to load the camper. I realized I had no idea how much weight she was putting into it. I thought momentarily about driving to a local stone quarry and having it weighed. That thought didn’t take root. Life is a gamble, right? Start to finish. In the end I loaded up a full row of firewood in the front of the truck bed, threw in the heavy cooler, hooked up and towed the load into a cold, gloomy, late October evening.

The first leg was 100 miles due south. There was a nasty, gusting crosswind from the west and it had me talking to myself for a couple of hours. I was sincerely wishing for another 50 horsepower and a heavier truck. Then we turned due west into the wind and things started settling down. I had Kathy drive to tell me how it felt compared to her half-ton pulling her old camper. She liked the feel of it. My heart rate was trying vainly to return to normal and her opinion helped a lot. Being married to an excellent driver is a blessing I hope you enjoy. I even started getting some honest hope that the next 6,000 miles wasn’t going to be a nightmare.

We crossed the fields and plains and wove our way into the mountains. The driving got easier. I never did get to the point the trailer salesman suggested (“You’ll never know it’s there!”) but mile after mile, the tension eased and we started having fun. We made Las Vegas a day early even though the normal approaches to the Hoover Dam were closed, causing long detours. We parked at an RV park just on the south side of Vegas proper and at the appointed hour, enjoyed talking about Blackstone to a large group of RVers.

Mountain driving got serious after we toured Death Valley and headed west across California. The climb out of Death Valley was memorable. From 282 feet below sea level to about 7,000 feet above in a very short stretch of road, we did our hardest climbing. Twice the steep grade got me down to second gear. That’s second gear on an Interstate highway and no one else was doing much better.

All this hard climbing, and all through the trip the coolant temperature didn’t vary at all. It just sat there like the needle was painted on. I’ve had normal cars overheat climbing up places like Pike’s Peak, just plain old cars with hardly any load in them. Here’s my Tacoma (we started calling it Taco-Ma) leaving Death Valley pulling 3,000 pounds of trailer and all the stuff Kathy packed in it along with a heavy cooler and a full row of firewood, and we got no variation in water temperature. I’m more than impressed. I’m amazed!

Gas mileage, however, was terrible. Normally Taco-Ma averages about 22 mpg on the highway. For the total trip, we averaged 12.6 mpg. There are long stretches of highway in the west where you can’t find gas. We had one “white-knuckle” drive that left us with less than a half-gallon by the time we found a station. After that, we started carrying four gallons in the bed of the truck.

Drive it like a bug

Towing the trailer reminded me of driving the original, underpowered VW Bugs. They could run about 70 mph on the flat, full-out. If you wanted to not slip too slow on the next upgrade, you held the petal to the metal on the downgrade and held it there, using momentum keep the speed from decaying. The end result is you keep the petal planted hard for most all hilly driving. Watch redline like a hawk. Shift when you must. Don’t let RPM sag too low. Driving like this, no wonder we lost ten mpg on this trip.

The drive took us to southern California for a couple of days, then back into Nevada and on down to Tucson for a couple more days. We crossed New Mexico, entered Texas down near El Paso where immigration problems are evident. We passed through a check station and as we approached we passed by a dozen sensors of some type staring us in the face, like so many cameras of a sort in a bank of equipment. They can apparently see through cars, trucks, and campers because they let us pass without much thought. There were no stowaways aboard.

We drove Texas diagonally ending up at Texarkana. You can drive 80 mph in southwest Texas. We didn’t. Could have, I suppose, though by that stage of the trip, I’d had enough of pushing the engine.

When Taco-Ma’s V-6 shoulders into a hard, long pull (which was invariably accompanied by Kathy and I shouting in unison, “Go Taco-Ma, go!”) you hear a sound of seriousness. The engine is an airpump. When you work it as hard as you can, throttle mashed to the floor, mile after mile, the serious roar is the scream of air intaking, passing through the core of the engine, and the jetting out of exhaust. It’s a heavy growl, an awesome sound. I’d heard it enough by the third week. And by then I was thinking seriously we might get home with no serious problems. The day-long drive across Texas was made about as cautiously as I could make it.

From the barren plains of Texas to the beauty of Arkansas was dramatic. Arkansas comparatively, looked like the Garden of Eden; like less populated parts of Wisconsin or Michigan. It also felt like we were closing in on home. Mountains and deserts behind us. Now just stay awake and drive.

We finally got to use the firewood in Tennessee. We burned it all in one night and what I learned was, the extra weight in the bed had been a nice asset. We had played with weights and balances daily for the trip, trying to find the magic balance for perfect handling. Turns out, using the firewood made the most difference of anything we’d tried. Less weight all around and almost none in the truck bed left the unit squirrelier than for any other trip leg.

The moment of truth

As soon as we got back I had the engine oil changed, along with any other gearboxes I hadn’t already changed out earlier. A day later my emailed report arrived. To my amazement and delight, engine wear hadn’t changed at all! Not a bit! The extra 1 ppm iron that turned up is from the longer oil change (6,672 miles vs. only 5,175 miles for the pre-trip sample). Iron tends to accumulate with more miles on the oil.

I was wrong in my assumption that towing and mountain driving would cause excessive wear. In large part I think this can be chalked up to the engine type. Perhaps it would have turned out differently had I been using old oil; the metals could have conceivably accumulated to levels that would have made the oil abrasive, which will cause excessive wear. But with clean oil, I didn’t find any change at all. Taco-Ma did us up right.

So will the same thing happen for you? If you run autocrosses or run at a drag strip or do anything other than ordinary driving, does your engine wear change as engine stress increases? Sometimes it does, but in the end there’s no hard and fast rule. So much depends on the engine, the driver, and the environment.

That’s why it’s no good to say all engines should have an oil change at 3,000 miles or 5,000 miles or beyond. The oil and engine combination that works for one guy may not work for the next, simply because all situations are different. It seems logical that if you don’t keep clean oil in the sump when loading the engine heavily, you will wear more at bearings. But if you run clean oil? Maybe no change. Try it and see.

By Jim Stark|2026-06-05T16:05:11-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

Space Dust

Here’s a fact. Everything we turn up in analysis of your used oil had to get in there somehow. As obvious as that may appear, I hadn’t really thought about it until I ventured into making my own oil.

I built it up gradually, starting with a 10W base stock that was nothing more than refined mineral oil with nothing added. After running it a specific period and measuring the results, I started adding components, running the same miles, and repeating measurements. Eventually I ended up with a complete package that performed very nicely.

Every time I changed something in the oil, the results were measurable. That led to a low-level Eureka! — an affirmation of something I’d always known but hadn’t given much thought: Everything we find in oil analysis had to get in the oil somehow. What we find in oil was put there by the oil blender, came from the engine, or came from the environment.

There are many factors and variables to consider in how long you can use oil in an engine and in how long an engine will last. The most important of all those variables is keeping the oil, regardless of type, as clean as possible. Your air and oil filtration systems are critical players in accomplishing this mission.

The importance of air filtration

Leaving oil filtration for another article, just how important is air filtration? It is one of the most important factors in long-lived engines and long oil change intervals. It is a variable you can control.

Silicon is everywhere in the environment. We rarely think of it unless we see a dust storm in a desert or watch a farmer’s tractor operating in a cloud of dust, but there is no such thing as clean environmental air. If you let rain drops dry on your car or truck, by the time they dry they will have collected enough dirt to leave spots on your paint.

Dirt exists everywhere because it comes from outer space. Have you ever wondered why the most important tool in archaeology is a shovel? If a team of archaeologists went to study a 2000-year-old humanity site, they probably would have to dig down 30 feet to find what they were looking for. The reason old things are buried so deeply is that the Earth is constantly being showered by extraterrestrial dirt. You can’t escape it, even at high altitudes, and they only way you can prevent it from prematurely wearing out your engine is to collect it in an efficient air filtration system.

Controlling the dirt

I was recently speaking with a pilot about why his engine was wearing so poorly. He told me he liked to pull a little carb heat (in other words, unfiltered air) through his engine once he hit altitude because the air up there wasn’t a problem. Once I looked at his report, I saw his silicon level was quite high. He was wrong about the air up there not being a problem. In fact, there is enough silicon in the air at any altitude to cause poor engine wear. It’s important for any engine to filter the dirt out before it can do damage.

All engines wear and eventually wear out. Assuming a mechanical or contamination event doesn’t cut short an engine’s life, the amount of wear an engine’s parts leave in the oil is predictive of how long that engine will last. One of the most destructive contaminants that get into the oil is excessive silicon. The best wearing (longest lasting) engines we see have air filtration systems that keep silicon to a minimum in the oil. Regardless of the air filtration system manufacturers supplied for your engine, it is up to you to maintain it to perfection. Is your air filter up to snuff?

By Jim Stark|2026-06-05T16:05:21-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

What’s the Best Oil Change Interval?

Here’s an interesting question we received recently from Pete, one of our long-time customers:

“Needed to ask you about AMSoil OE synthetic oil. The change interval that is suggested for that oil is whatever the vehicle manufacturer has specified for that particular vehicle. But what have you seen from the TBNs that you have run on that oil? It doesn’t make sense that in my old 01 Maxima it would only be good 3000 miles but in a brand new vehicle it could be good for 10K.”

Pete has a point. Why would the same oil wear out faster just because the manufacturer recommends a shorter oil change interval? If the oil can hold up for 10,000 miles or more in some engines, shouldn’t it be able to do so in any type of engine?

Of course, there are some reasonable explanations that Amsoil (or any oil manufacturer) might give for this. The industry is generally moving towards longer oil change recommendations because modern engines are built to more exacting standards than they were even ten years ago, allowing for improved efficiency and less damage to the oil.

Plus, you might have to adjust the oil change interval in the same exact engine based on whether you’re seeing “severe” duty or not, so it’s probably reasonable to think that some types of engines would just treat the oil a little more harshly, and require a shorter oil run, right?

The cynical side of me, though, says that the real answer to this question probably has more to do with the legal department than the oil’s engineers. Regardless of how good you think your oil is, if you start telling customers they can ignore the original engine manufacturer’s recommendations, you’re probably opening yourself up to some legal headaches that the head office just doesn’t want to deal with.

But true as that may be, it’s not a very good answer for Pete, or the rest of our customers who are just looking for the best advice on how to treat their vehicles. So setting aside specific recommendations for a moment, let’s get to the nut of Pete’s question… Does the life expectancy of the oil change based on what engine it’s used in?

The tale of the TBN

There are several factors that we use to determine if your oil can be run longer, but Pete asked specifically about the TBN, so let’s focus on that for now.

For those who don’t know, the TBN (Total Base Number) measures the amount of active additive remaining in the oil. A typical gasoline-engine oil might have a starting TBN between 6.0 and 8.0, while diesel-use engine oils tend to have higher TBN’s of 11.0 or 12.0, since they have to deal with dirtier, more acidic conditions.

But regardless of where a TBN starts, they all end up in the same place—0.0—if the oil is run too long. Once the TBN is down to zero, it means that the oil is no longer able to neutralize acids produced by the engine. As a general rule of thumb, we usually say that once a TBN gets lower than about 2.0, it would probably be a good idea not to run the oil much longer, to avoid running out of those active acid-neutralizing agents.

To answer Pete’s question about how the TBN of Amsoil OE holds up in different engines, we searched our database to find the recent TBN results we’ve seen from that type of oil. Since the TBN is an optional test, we don’t run it on every sample we see, but customers who use Amsoil tend to be pretty interested in seeing how long they can run their oil, so we have a pretty good representation for that oil type. We plotted nearly 50 samples’ TBN results against the mileage on the oil, and came up with this graph:

The banana-shaped line we’ve drawn approximates the “average” TBN for this type of oil over a given mileage. You can see that the TBN tends to drop quickly at first, but the longer the oil is run, the slower the TBN drops. Of the samples we tested, none of them had a TBN less than 1.5, so even on very long oil change intervals, this Amsoil OE oil tends to retain plenty of active additive.

Also note that the actual test results (the dots) can stray pretty far from that line on either side, so even though the TBN readings tend to follow a particular pattern, there can be a pretty wide deviation in individual test results. Just at a glance, you can easily see that the sample with the highest TBN reading didn’t have the lowest mileage on the oil, nor did the sample with the longest oil run (a whopping 18,500 miles) have the lowest TBN reading. In fact, the lowest TBN came after a fairly middle-of-the-road 8,569-mile oil change interval.

And before we get too hung up on looking at just Amsoil OE, we ran the same analysis for one of the most common oil types we’ve tested, Mobil 1 5W/30, resulting in the following chart:

The graph for Mobil 1 5W/30 covers nearly 5,000 samples with TBNs, and the scale is a little different than the Amsoil OE chart, but you can see that banana-shaped curve that we’ve drawn, approximating the average TBN for a given mileage, is exactly the same as in the Amsoil OE chart. Once again, the highest TBN was not the shortest oil run, and the lowest TBN was not the longest oil run. So even though we have many more TBN data points for Mobil 1 as we do Amsoil OE, the overall trends for TBNs are similar, and would be with just about any type of oil you could name.

What affects the TBN?

So what other factors might be affecting the TBN? To find out, we ranked all the samples according to both mileage and TBN reading, and came up with the best and the worst of the bunch.

One factor that definitely stood out was make-up oil. If you add some fresh oil in between oil changes to top up your oil level, you’re infusing the oil with more active additives, and diluting wear metals and contaminants at the same time. That’s why we often say that you shouldn’t be too upset about adding a quart or two of oil over the course of your regular oil interval (assuming you don’t have a noticeable leak, of course), since that fresh oil might buy you a few thousand extra miles before you have to do a full oil change.

In this case, all of the samples that noted adding a quart of oil or more ranked in the top half of the results, and the Amsoil samples with the most oil added (2.5 and 3 quarts) ranked at numbers 2 and 7, respectively. On the other hand, the overall best-ranked sample, with a TBN of 4.0 after 10,000 miles, didn’t add any oil in that time, according to their oil slip, so make-up oil alone is not the only relevant factor.

Pete’s original question was about manufacturer’s recommended oil change intervals. We don’t have a list of the recommended OCI for every engine we’ve tested, so we’ll have to settle for looking at some other factors, like the age and size of the engine.

For both the Amsoil and the Mobil 1 samples, the age of the engine didn’t seem to make much of a difference. We had engines from the late 90’s and early 2000’s in the top ten percent on both charts, mixed right in with new engines from the last few model years. The total engine mileage was also mixed, with higher-mileage engines ranked right alongside brand new engines in their first few oil changes.

Engine size is one factor that I thought would end up playing a pretty big role, but I wasn’t sure which way it would go. On the one hand, larger engines tend to work harder, so I wondered if the larger 6-cylinder engines and big V8s might burn through the active additive more quickly than smaller engines. On the other hand, 4-cylinder engines also tend to have smaller oil sumps, meaning less total oil volume in the engine, so maybe their active additives get used up sooner.

Mixed results

Turns out there results were pretty mixed as well… there was a bit of a trend for smaller engines to hold a higher TBN for longer oil runs, but there were plenty of larger engines near the top ranks of both lists, and vice versa. Seems like the extra oil in the sump of the larger engines pretty much balances out the extra work they have to do, resulting in a mostly even distribution of engine sizes across the rankings in both charts.

So what does all this tell us? Well, at least as far as the TBNs go, it doesn’t look like the type of engine has much of an influence on how long the active additive lasts in the oil. Engines of the exact same type (and in some cases, even the exact same engines) were ranked both high and low in our results, so it looks like individual driving habits and the behavior of each particular engine play a much larger role than engine sizes, model years, manufacturers, or any other criteria we could see.

When you get right down to it, though, the TBN is only one factor in determining whether or not it’s safe to run the oil longer. It’s a valuable tool, but we also have to look at other factors, like wear metals, insolubles, viscosity, and contaminants, any of which could indicate that you shouldn’t run the oil any longer, even if the TBN is still good.

The bottom line is this: the lawyers have to tell you to follow the engine manufacturer’s recommendations, since they have no idea what’s going on with your particular vehicle. And really, the original engine manufacturer doesn’t have much better of an idea—they know how their engines should wear, and base their recommendations on what should work best for most drivers, but they don’t have any idea about your particular driving habits or maintenance routines.

When you get your oil analyzed at Blackstone, we’re looking at the specific conditions for your specific engine, which is why we can tell you if it’s safe to add an extra 2,000 or 3,000 miles on your next fill, regardless of your current OCI. Just check “Yes” next to the question “Are you interested in extended oil use?” on the back of your next oil slip, and maybe you too will be free to explore the world of extended oil use!

By Travis Heffelfinger|2026-06-16T15:12:55-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|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|2026-06-05T16:06:13-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

Does Oil Brand Matter?

No matter who you are or what your oil analysis needs are, you have undoubtedly faced the question on everyone’s mind these days: What type of oil should I use?

Many people have very strong loyalties to certain brands of oil. They’ll swear by their favorite brand and assure you that anything else is bound to ruin your engine. But we’re here to dispel that myth. After nearly 30 years of testing oils from thousands of different engines and industrial machines, we have discovered a shocking fact: it doesn’t really matter what brand of oil you use.

But wait! Before you dismiss us as heretical, listen to what we do recommend. We always suggest using an oil grade recommended for your engine by the manufacturer and a brand that fits your budget. The grade of oil is much more important to performance in your engine than the brand of oil.

In fact, here’s another little secret. The oils you can find at any mass retailer, such as Wal-Mart or Meijer, are actually name-brand oils (such as Valvoline, Shell, or Quaker State), but with the store’s label on it. Think about it. A place like Auto-Zone is not in the business of manufacturing oil. They buy their oil from the big oil companies and put their name on the bottle. The only difference between the Auto-Zone brand and the name-brand oil is the name on the bottle and a few dollars per quart.

We analyze oils from our personal use engines (right down to our lawn mowers) religiously. We tend to choose oils that do not contain additives that can get in the way of elements we want to see in the analysis. For instance, many light, multi-grade oils use sodium as an oil additive. The sodium can mask antifreeze contamination.

If you want to see for yourself which oil is going to perform better in your engine, we recommend a test: run Brand A in your engine for a set number of miles or hours and have a sample analyzed. Then run Brand B in your engine for the same amount of time, and have that oil analyzed. You can compare the results for yourself, side by side, to determine which oil is best for you.

By Jim Stark|2026-06-05T16:06:30-04:00July 28, 2023|Articles, Gas/Diesel Engine, Industrial, Marine|Comments Off

Do I Need to Worry?

Last month we got an email from John, who had some questions about his report. His F250 was showing traces of coolant in the oil, and lead, from bearings, was elevated. He had the engine out of the truck pending repairs and wanted to know: how much lead is too much? Did he need to replace the bearings?

“Do I need to worry?” is a common question, and one there’s not one easy answer for. We’ve had people pull the bearings out of a Corvette when lead was only a few ppm above average and we said in the report, “You don’t need to do anything about this yet.” (For the record, that guy called us and said his bearings looked fine and was kind of honked off about it.)

We’ve had people with metals that are high all along, but not changing, and it never turns into a problem. And we’ve had people not pursue what appeared to be a problem, and regret it in the end (this is especially problematic when the engine is in an airplane).

So how do we decide what’s a problem and what’s not? It would be great if there was a magic number, but there’s not. We assess each engine individually, mainly focusing on these things:

How your sample compares to your trends
How your sample compares to average
The balance of metals to each other
Whether you’re using additives

Trends

If you have them, trends are the most helpful thing we look at in determining your engine’s health. It takes three samples to get a good trend going (though we can often tell if something is amiss earlier than that).

All engines are different, as are their drivers, how they’re used, and where they are in the country. As such, it’s very helpful to sample a few oil changes in a row, at least at first, and have a baseline established for your specific engine. Consistency counts. If your engine is wearing a lot but it’s doing so steadily, it’s possible that the metal isn’t a problem. Problems tend to get worse over time – not remain stagnant.

Figure 1 is a good example where lead (a bearing metal) doesn’t appear to be a problem. That engine has more lead than average, but it’s consistent. Since the owner wasn’t having any problems, our recommendation was to just watch lead as time goes on.

But on the other hand, look at Figure 2. Lead read at just 12 ppm in this sample—that’s well within the average range, but we marked it because lead had always been much lower than this. If this had been his first report, we might have thought lead was okay. But since we know that lead is usually low, we told him the bearings are wearing more than they were and to watch for abnormalities like low oil pressure.

Universal averages

Of course, when you start sampling, you don’t have trends to rely on. So our second line of defense, when we’re looking at your numbers, is universal averages.

We have averages established for most of the engines out there, though we’re always adding to our database as new types of engines (and transmissions and generators and other machinery) are being made all the time. When you do your first sample, we’ll compare your metals to averages for your specific engine.

It’s helpful for us to know what kind of engine you have. Look at Figure 3, for example. This is a comparison between the Toyota 1.8L 1ZZ-FE (used in Corollas and Vibes), and the Oldsmobile 455 (used in older motorhomes and the Cutlass and Trans Am). Toyotas don’t wear much, whereas the Olds 455 makes a lot of metal.

If we don’t know what kind of engine you have, we might end up comparing your numbers to the wrong set of averages, or just a generic engine file. We can still tell if something is way out of line, but the more subtle differences between your engine and averages are harder to see.

Along those same lines, some vehicles come with many different engine options, so just telling us the year, make, and model of your vehicle isn’t always enough. The 2006 Silverado, for example, could have one of five different gas engines or the 6.6L diesel engine in it. We have different averages for each of those engine types. Take a look at Figure 4. The metals are similar in those engines, but they’re different enough to matter when we’re determining if something is too high or not.

Generally speaking, we’ll mark a metal in bold when it’s twice average or more. But not always—there are also times when we don’t mark elevated metals, if we know something else is going on.

We test a fleet of armored Sprinter vans that operate in New York City, for example. The vehicles are loaded up with armor and spend their entire lives idling and driving in unforgiving traffic conditions. It’s no surprise that the engines wear more than average. (See Figure 5.)

Balance of metals

We also look at the balance of metals relative to each other. In Figure 6, lead is not reading twice average but we marked it anyway. According to averages, lead and iron should be at about a 1:1 ratio. In this sample, the lead: iron ratio is more like 4:1. This balance tells us the bearings are wearing more than the rest of the engine, and that can be a sign of trouble too.

Additives

Another factor to consider is the use of additives and/or leaded fuel. Lots of people use Restore, which has copper and lead in it, and although in that form those elements aren’t harmful, they do make your numbers read high.

Likewise, if you’re using leaded fuel, racing fuel or certain octane boosters, fuel blow-by will cause high lead readings. The highest lead reading we’ve seen in any BMW S65 engine was 1055 ppm. The rest of the metals looked great, though, and the customer had mentioned using an additive, so we were pretty sure the lead in his sample wasn’t a sign of an impending bearing failure.

How much metal is too much?

So how much metal is too much? In truth that number is different for every engine. You already know that we take a lot of things into account in trying to answer that question. Usually we’ll call you to get more information if we’re not sure, and we’ll suggest giving it an oil change or two to see how trends shake out. If something is seriously out of line we can usually tell, even if we don’t know your engine type or how you use it.

We will say this, though: it’s pretty rare for a major mechanical problem to happen unexpectedly overnight. Most engines will give at least some warning before things go south, and that’s why you do analysis. Follow the trends to see what’s normal for your engine, and when deviations occur, you’re informed enough to make a good decision.

By Kristin Huff|2026-06-05T16:06:45-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

Better Mileage with Synthetic?

One afternoon a customer emailed us and said he gets better mileage when he’s using synthetic oil. To be honest, we were skeptical. If you’ve been with us long enough, you know we generally think that oil type doesn’t matter. Use Oil A for 5,000 miles and do a sample to check your metals, then use Oil B for the same miles and resample. Most people will find that their engine wears just the same regardless of oil brand. But here is an angle we hadn’t tested — is fuel economy affected by your choice of oil? We decided to try and find out.

Designing the experiment

When we first started talking about a fuel economy experiment, we came up with a lot of questions. How will we know how much fuel we’re actually using? How will we take into account tire pressure and other things that can affect fuel economy? Do we need to take into consideration the natural expansion of gas at different temperatures?

We eventually decided on the following plan. It’s probably not scientific enough for a MythBusters special, but it’s about as good as we could get without installing special pumps and meters, and it should be repeatable if you want to give it a shot in your own vehicle.

Counting miles was the easy part — we just recorded miles at every gas fill-up. Figuring the “per-gallon” was a little trickier, since we don’t really have an accurate way to measure fuel consumption.

In an episode of MythBusters where they were doing something that involved calculating miles/gallon, they took an old clunker, removed the hood, and rigged up a container that measured fuel consumption to the milliliter. That’s a little more involved than we wanted to get, especially since our guinea pigs are analysts Amanda and Alex’s daily driver vehicles.

We ended up recording the number of gallons needed to fill up at the pump. We decided to resist the urge to “top-off” the tank when filling and just stop pumping whenever the pump stopped. Is this a perfect measure of fuel usage? Certainly not. Every pump could be a little different in its stopping point depending on the day, the pump, the volume/speed of fuel dispensed, ambient temperature, and so on…but these things are impossible to control in the real world.

We decided to do ten gas fill-ups on each type of oil. With ten fill-ups, we’d have enough data to take into account some of those variables mentioned above that we can’t control. We also made a note to monitor tire pressure, though that varied so little that we thought it negligible.

Royal Purple vs. Quaker State

Amanda started with Quaker State Advanced Durability 5W/20. The price at O’Reilly Auto Parts was $5.29/quart or $23.99 for a handy 5-quart bottle, which is just perfect for her Kia, which takes 4.8 quarts of oil. She ran that oil in her car from May to June 2013. In ten gasoline fill-ups, she ran 3,703.7 miles and used 131.858 gallons, for a fuel economy of 28.09 miles/gallon.

She decided that 3,703.7 miles was too early to change her oil, so she kept running that oil for a total of 6,333 miles and changed the oil on July 27, 2013. The result was some good wear numbers (see figure 1, F66495).

On to the synthetic! Royal Purple 5W/20 costs $9.79/quart at O’Reilly Auto Parts and does not come in a handy 5-quart jug, so we ended up paying $48.95 for oil on this oil change. Amanda ran this oil from the end of July until October, going 3,829.2 miles and using 137.002 gallons of fuel, for a final fuel economy of 27.95 miles/gallon, a decrease of 0.5% compared to the Quaker State conventional.

Oil	Price/5 gal.	Miles	Gals.	MPG
Quaker State 5W/20	$23.99	3703.70	131.89	28.08
Royal Purple 5W/20	$48.95	3829.20	137.00	27.95

Amanda ran the Royal Purple a total of 14,277 miles before changing it (we’re all for getting our money’s worth out of an oil change!), and ended up with a little more wear than usual (figure 2, G22246).

The two oils are very close in terms of fuel economy, with the conventional Quaker State slightly edging out the more expensive Royal Purple. But in the spring of that year she was doing a little more highway driving than in the fall, with a few trips between Illinois and Green Bay, Wisconsin, and so on. Even so, the added cost for the oil itself almost certainly defeats any slight improvement in MPG she might have gotten. So let’s look at Alex’s numbers.

Mobil 1 vs. Mobil Super & Advance Auto Parts 5W/30

Alex spent $34.85 for five quarts of Mobil 1 Advanced Fuel Economy 0W/30 at Wal-Mart and ran the oil from January 2013 to May 2013. He traveled 3,061.1 miles, used 91.3 gallons of gas and ended up with a fuel economy of 33.53 miles/gallon.

Then he bought five quarts of Mobil Super 5W/30 conventional oil for $18.10 and ran 3,234.9 miles on 92.0 gallons of fuel from June to October 2013, for an average fuel economy of 35.16 miles/gallon¾a difference of 4.9% in favor of the conventional oil.

Oil	Price/5 gal.	Miles	Gals.	MPG
Mobil 1 AFE 0W/30	$34.85	3061.10	91.30	33.53
Mobil Super 5W/30	$18.10	3234.90	92.00	35.16

Alex noted that his engine tends to get better fuel economy in general in the warmer months than the colder months, so he repeated the experiment again the following year, using Advance Auto Parts 5W/30 conventional oil from February to March 2014, getting 32.93 MPG.

He then ran Mobil 1 Advanced Fuel Economy 0W/30 from May to August, getting an average fuel economy of 34.46 miles/gallon. In this case, Mobil 1 did beat the conventional oil, but his mileage still wasn’t as good as on the original run of Mobil Super 5W/30 conventional, and the added cost of the oil negates any extra miles-per-gallon.

Alex mentioned that on synthetic oil his engine seemed to burn less oil, but since that wasn’t the point of the experiment, we didn’t get too deep into trying to quantify that.

Synthetic or conventional?

So…which oil to choose? We get asked this question hundreds of times a year on the phone, in e-mails, and written on oil slips. And honestly, from a wear standpoint, we don’t find a lot of difference between conventional and synthetic oils. Some engines may run better on one than the other, or maybe you find that your engine uses less oil on one or the other, but these things are hard to quantify from our end.

There are so many factors that affect how your engine wears, what kind of mileage you get, and how long your engine will last that we could never issue a blanket one-size-fits-all statement saying “You should use X.”

We did not find that synthetic oil gave us better fuel economy, but that doesn’t mean that you won’t. Feel free to try this experiment at home and let us know what you find. Or, if you’re not experimentally-inclined and you’re wavering about what oil to use, feel free to use whatever fits your wallet. Any API-certified oil is going to be quality oil, and your engine should be happy with whatever you choose.

By Amanda Callahan|2026-06-05T16:06:55-04:00July 28, 2023|Articles, Gas/Diesel Engine|Comments Off

Antifreeze: The Silent Killer

After analyzing engine oil for 30 years, I can safely say the thing that kills more engines than any other is antifreeze seeping into the oil. We call it the “silent killer” since there is normally no indication this dreadful contaminant is about to strike until after the damage is done. Neither you nor your mechanic can see it in the oil. The dealer won’t know it’s there.

We like to say engines speak before they fail, but in this case, you aren’t likely to hear much of anything until you hear just about the worst sound an engine can make. Oil analysis is the only way of knowing this sneaky killer is closing in on you. We can see it in the oil at a trace level, long before any harm is done.

We call people daily to let them know anti-freeze contamination is about to ruin their day. A typical reaction is, “What? That engine is running fine!” And they are right—the engine will, in most instances, run perfectly well until a bearing spins, oil pressure drops, and the engine destructs to the point of no salvation.

Some engine configurations are more susceptible to the problem than others: V-6s and V-8s for instance, are perhaps more prone than other engines. But no engine is immune (except air-cooled engines!). One would think that after 100 years of building engines, the automakers would get it right. To my knowledge no one has.

The problem with design

The engineers who design engines do a marvelous job of building lighter, more efficient and faster engines. But for every step forward in the process, there are compromises.

Building lighter engines necessitates working with new alloys for the various parts that are bolted together. Gaskets are used to seal between the parts. To get an engine perfectly right, they have to use parts that expand and contract with heat at the same rate, and gaskets that are hardy enough to seal well even after they age and suffer millions of heat cycles. You can imagine the engineers tossing in their sleep while wrestling with this dilemma.

A classic example of the problem was a Jaguar in-line 6-cylinder engine I once owned. I loved that engine with its long, high-end torque curve and mellow growl. It was probably the first duel overhead cam design that managed quiet chains in the days before belts were used. But for all its wonderful assets, there was this one drawback: they used an aluminum alloy head on a cast iron block. If you managed 50,000 miles on a head gasket, you were a very fortunate person.

With an in-line design, the anti-freeze contamination usually develops at the head gasket. With the V-designs, a more common source of the problem is intake manifold gaskets.

The manifold gasket supports the air/fuel system mechanism and straddles (and is bolted to) the heads. You can imagine the complexity of the problem of heat cycles. Block expansion forces the heads up and away from the crankshaft. The lowly intake manifold is not in a position to move in concert with the expansion. It would be like trying to ride two horses standing on the two saddles.

The result of this set-up is that intake manifold gaskets fail. Antifreeze starts seeping into the oil. It often takes quite a long while before the problem manifests itself in a failure, but it can also happen quickly. Since there are usually no obvious symptoms of the problem, the unwary engine owner usually drives the engine to oblivion.

Another common question we hear is, “How long until it fails?” Unfortunately, it’s impossible to predict how long an engine with an antifreeze problem will last. Many variables factor into the equation: the type of engine, how it’s driven, the environment it’s operated in, and—the most unpredictable of all—Lady Luck. Some people can limp along for ages with a slight trace of coolant that never turns into anything serious. Others turn up a trace and then WHAM! Faster than you can say “spun bearing” the engine fails.

Don’t quote me on this, but if I had to estimate the severity of the problem in car and truck engines today—judging from our oil samples—I would suggest 1–2 % of the cars and trucks in the road today are in the process of failing from antifreeze contamination of the oil. Fortunately, most antifreeze problems can be detected early with oil analysis, and in most cases we can save the engine before a failure. We would like to save all of them. But we can’t save anything until see the oil from it.

By Jim Stark|2026-06-05T16:07:08-04:00July 28, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off

The eBay Oils (Part 3)

Welcome back to the eBay Oils! If you missed the previous two installments, wherein we describe what we found in some old oils that Ryan bought on eBay, you can read them here and here.

HyVis 4 Winter

We’re going to kick this party off with an oil that I personally have never heard of: HyVis 4 Winter Motor Oil. The can looks very groovy and it has no zip code, so I’m placing it from the very early 1960s or late 1950s. It’s “Mileage Metered” and it has a picture of a medal with a ribbon on the can, so you know it’s good stuff. HyVis was apparently way ahead of the curve on extended oil use, because on the top of the can it says it’s good for 1,000 to 9,999 miles. Interestingly, the oil has zero additive in it (Figure 1). Or perhaps it’s got additive in it, just not any that we read. The grade is not listed on the can, but the viscosity came back as a light 20W. With the lack of additive it’s not surprising that the TBN read 0.0. It’s tempting to do an experiment and run this apparent mineral oil for 10,000 miles in the dead of winter, just to see what would happen. If you know of any guinea pigs, send them our way!

Amoco LDO 10W/40

Next up is a pair of old oils: Amoco and Texaco. These names remind me of gas stations we’d stop at on family vacations in the 1970s. Amoco (which he always pronounced Uh-muck-o) is the one that reminds me most of my Dad. Amoco gas stations were called Standard stations in some parts of the country, and I’ll always associate the blue, red, and white logo with long trips across the country in our green van with the velour bed and hanging beads. But Amoco did more than fill up gas tanks in the 70s–they also sold oil, and this “Long Distance” version is an SAE 10W/40. The additive package looks a lot like the Mobil Special oil we saw: heavy on phosphorus and zinc, lighter on calcium and magnesium (Figure 2). Just the right oil for a couple of bandana-wearing hippies traveling with two little kids from Indiana to Nova Scotia in 1976 in a green van with a sunset painted on the side. Ah, the ’70s.

Texaco Ursa ED 20-20W and Texaco Havoline Super Premium 10W/40

The Texaco Ursa ED oil is scant on advertising copy. They must have had their hands full designing this “Extra Duty” 20-20W oil instead. On the can they recommend this oil for everything you can think of except lawn mowers. It’s got a lot of additive in it (Figure 3), but the additives are configured more like what we’d expect out of a gear lube ¾ except with more calcium. Why the 20-20W and not just 20W? We’re not sure. Maybe it’s fancier. The viscosity read like what we see today out of a standard 5W/30. Texaco Havoline Super Premium 10W/40, on the other hand, looks a lot like one of today’s diesel-use oils in additives (Figure 4), with a normal 10W/40 viscosity.

Lucky Strike 20-20W

We knew Lucky Strike made cigarettes, but we had no idea there was an oil of the same name until Ryan found this can and bought it on eBay for $29.99. The can looks seriously old, with no information on it beyond the name, a picture of an oil derrick, and the words “One U.S. Quart.” A quick Google search revealed no real information¾just some old Lucky Strike Oil & Gas Company stock certificates from 1917. The oil probably isn’t quite that old, but it may very well be the oldest of all the cans we bought. They didn’t do a lot with additives back then, though we did turn up 125 ppm barium (Figure 5). Not a lot else was present in this 20-20W oil. Note that without any calcium or magnesium, the TBN read 0.0.

Union 76 20W/50

Union 76 20W/50 is clearly made for speed. You can tell because of the black-and-white checkers on the front. According to the lid, this oil was tested and certified by the national association for stock car auto racing. My friend Google tells me that stock car racing became popular back in the 1920s (when moonshiners were outrunning Johnny Law during Prohibition times), but this can is clearly not that old. Not only did they not make multi-viscosity oils that long ago, but the can comes from zip code 90017 so it has to be from 1963 or later. According to the can, it’s 100% parrafinic oil with selected additives, which our spectrometer reveals to be your standard line-up of calcium, phosphorus, and zinc (Figure 6). Look at that viscosity though¾it’s higher than we see in today’s 20W/50s.

Castrol R Racing

Who doesn’t love Castrol? Other oil companies, that’s who. But we like them all right, so we bought two old cans. One, with liquid tungsten, we reviewed in the first article in this series. The other appears to be much older: I’d place it from the 1940s or 1950s. Not only does this can have a high opinion of itself (“The Masterpiece in Oils!”), but they direct you how to ask for it at the store: “Do not ask for ‘XL’ or ‘XXL.’ Always state the full name.” Like modern oils, they stress the high quality of the oil with terms like “organo-metallic” that are meant impress those of us who aren’t in the oil business. I don’t know if I’d call this a masterpiece in oil work though: it looks like what we see out of ATFs these days as far as additives go (mostly phosphorus with a little zinc thrown in). Since the word “Racing” is stamped into the top of the can, the thick viscosity (like a 50W) makes sense (Figure 7).

Sinclair Dinolene 20-20W

I’ve always had a soft spot in my heart for Sinclair. The can has a picture of a dinosaur on it! This shit came from the ground, no doubt about it! Another 20-20W oil, the oil is light on advertising copy but heavy on additives. In fact, it looks a lot like recent versions of Shell’s Rotella 5W/40, except with a little less calcium. It’s much lighter than Shell’s 5W/40, though, with a viscosity reading like a 30W or a heavy 20W oil. Note the presence of lead (Figure 8).

Amsoil Super Premium 10W/40

Until I started writing this article, I had no idea that Amsoil has been around since 1972. This particular sample came, like all the rest, from a can, so it has to be at least from the mid-’80s (which is when most companies switched to plastic bottles). Even 30+ years ago, Amsoil was pushing 25,000-mile oil changes, and the can even lists a comparison between this oil and regular old petroleum as far as engine temps, flashpoint, oxidation, and lubrication range (unsurprisingly, Amsoil wins in each category!). Modern Amsoil products tend to be heavy on additives and that was true back in the day as well (Figure 9). Just for fun, we compared this oil with a virgin sample of Amsoil 10W/40 that we ran in February 2012 and they look a lot alike. The only difference is in the older oil there’s less of everything: 500 ppm less calcium, and 100-200 ppm less phosphorus and zinc. They used magnesium in the older oil, while the TBN and viscosities were nearly identical.

Pennzoil Dex2 and Z-7 10W/40

Pennzoil started as Penn’s Oil in 1913, and I have to admit, “Why the Liberty Bell?” was my most pressing question as I looked over these two old cans. Originally, Penn’s Oil came from an oil field in Pennsylvania and was christened with a Liberty Bell logo to remind users of its Pennsylvania roots. This can of ATF clearly has an earlier generation of logo on it, and Google informs me that Dexron II was introduced in 1972. This may very well have been the transmission oil that kept our green van chugging through the ’70s. There are a lot of different ATFs in stores today, though generally they have about the same additive configurations. This one is a little different in that it has more boron, magnesium, and zinc than most modern ATFs. The viscosity is right where we’d expect it to be though. Pennzoil’s 10W/40 oil can is flashy, a la the 1980s. It’s “The Motor Oil With Z-7” and although they don’t specify what that is, they do specify that “You need no extra oil additive.” So that’s reassuring. It’s rated SF-SC-CC, so I’d place it at about 25 years old. Maybe the magic of Z-7 is copper: that’s something we saw a lot of back in the day, when Blackstone was founded. Interestingly, magnesium is the dominant additive in this one, followed by zinc, phosphorus, copper, and boron (Figure 10). The flashpoint was lower than what we see today from 10W/40s.

Renuzit

At last, we finish our tour of ancient oils. (Some of these samples are older than the people reading this article. This makes me feel very old. Hey, get off my lawn!) I said before that I thought the Lucky Strike was the oldest of the oils we tested, but that’s only because I forgot about this can of Renuzit sitting in Blackstone’s garage. It’s rusty on the bottom so it leaks, and it’s not from a can like the others. This one was sold in a 5-quart metal jug. I particularly love this one, because the can not only says you’ll “Cut Your Oil Bills In Half,” but the first point of advertising on the side is a “Faster Getaway!” Now, they don’t actually say that this is the choice of oils for bank robbers, but I know if it was 1941 and my hungry Great Depression self was contemplating which oil to put in my Ford Special for bank-robbing time, this is the oil I’d pick. With practically no calcium or magnesium present, the oil’s TBN read 0.0, but it does provide would-be crooks with phosphorus, zinc, and barium as well as a 20W viscosity for the getaway (Figure 11). When you’re busy working a tommy gun, the last think you want to think about is whether or not you’ve made the right choice in oil.

So that’s the end of our series. A lot of thought goes into making oil, and that’s been the case for many decades now. We’ve poked some fun at the way oil companies sell their products, but heck, they’ve got to say something. We stand by our statement that “oil is oil” and in the end, it doesn’t make a lot of difference what you decide to use. Through all the years and all the permutations and configurations of oil and oil additives, the crude (and now, synthetic) stuff has kept cars running since Henry Ford did his thing more than 100 years ago. Buy what suits your vehicle and your wallet¾not what anyone else says you should use!

By Kristin Huff|2026-06-05T16:07:19-04:00July 20, 2023|Articles, Gas/Diesel Engine, Marine|Comments Off