Generally speaking, the higher an oil’s total base number (TBN), the better its ability to neutralize contaminants such as combustion by-products and acidic materials. TBN is a measure of (alkaline) additives in the oil. Higher TBN oils are able to neutralize a greater amount of acidic materials, which results in improved protection against corrosive reactions and longer oil life.TBN levels are targeted for the intended application. For example, gasoline motor oils typically display lower TBN numbers, while diesel oils must manage the high contaminant-loading from soot and sulfur and typically have a higher TBN.

TBN levels decrease as the oil remains in service. When the level reaches a point where it can no longer protect against corrosion, the oil must be changed.

Oils that are formulated specifically for extended drain intervals typically display elevated TBN to ensure proper corrosion protection for the duration of the extended interval.

AMSOIL Advantage – High TBN

Because AMSOIL synthetic lubricants demonstrate consistently high TBNs, they neutralize acidic contaminants and keep them in suspension to prevent corrosion, maximizing engine protection. AMSOIL lubricants use detergent and dispersant additives to significantly reduce sludge and carbon deposit formation. In the Total Base Number Test (ASTM D2896), AMSOIL Signature Series 5W-30 Synthetic Motor Oil demonstrated the highest TBN of the oils featured in the test, helping it deliver reliable protection for extended drain intervals.

Note: These test results describe and represent properties of oils that were acquired November-December 2012. Results do not apply to any subsequent reformulations of such oils or to new oils introduced after completion of testing. All oils were available to consumers at the time of purchase. Testing was completed February 2013 by an independent, third-party lab. Formulations were coded to eliminate bias, and samples were tested in random order. An appropriate number of trials of each oil were run to produce results at the 95 percent confidence level when compared to AMSOIL Signature Series Synthetic Motor Oil.