TAN and TBN

It is the neutralization value of used engine lube oil. 
The ability of an oil to react with a base reagent which indicates the acidity expressed as TAN. 
The ability of an oil to react with acidic reagent which indicate the alkalinity expressed as TBN.
The results are expressed intern of milligrams of potassium hydroxide (KOH) required to
neutralise one gram of sample oil for both TAN and TBN. 
 TBN for an oil used for 
 
Crosshead type diesel engine crankcase is 8mg KOH/gram of oil. 
For trunk type engine using heavy oil is 30mg KOH/gram of oil.