Description

Save money on oil changes – bundle a Total Base Number with your standard analysis for a complete evaluation of whether you can run your oil longer than you normally do. The TBN is only for engine oil – not transmission or gear oil.

The TBN measures the amount of active additive left in the oil. It’s a good test if you want to run your oil longer than you have been (we call this “extended oil use”).

Typically a TBN starts out around 6 or 7 in gas-use oil and 9 or 10 in diesel oil. As you run the oil, the active additive gets used up. Once a TBN reaches 2.0 or less, we consider that too low to continue running the oil.

Interestingly, the TBN doesn’t drop in a straight line down. If you were looking at a graph, the rate of TBN depletion would be more of a curve. The TBN drops quickly at first, and then more slowly after that.

You don’t necessarily need a TBN for us to give you a recommendation on how long you can run your oil, but it can be a helpful guide to determine if the oil is up to extended use.