Oil + TBN


Get a TBN with your standard engine oil sample! The standard sample with TBN includes:

  • Spectral exam
  • Viscosity
  • Insolubles (total solids)
  • Flashpoint (checks for fuel and other contaminants)
  • A Total Base Number, which measures the amount of active additive remaining in the oil. Good for exploring extended oil changes.
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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.

Additional information

Oil type

Gas/Diesel, Marine

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