TBN Booster from Hot Shot’s Secret will raise your diesel engine’s oil TBN number up to 6 points and save 2-4 oil changes per year. TBN stands for Total Base Number. It is a measure of how much active detergent and dispersive additive is left in your engine’s oil. A TBN rating of 6-9 is typical. As miles are added, the TBN number decreases as the detergent and dispersive additives are used up. When TBN less than 5, your oil has lost its effective capacity to neutralize acid and breakdown dirt.