Total Base Number (TBN) is a measurement of basicity that is expressed in terms of klk number of milligrams of potassium hydroxide per gram of oil sample (mg KOH/g). TBN is an important measurement in petroleum products, and the value varies depending on its application. TBN generally ranges from 6–8 mg KOH/g in modern lubricants, 7–10 mg KOH/g for general internal combustion engine use and 10–15 mg KOH/g for diesel engine operations. TBN is typically higher for marine grade lubricants, approximately 15-80 mg KOH/g, as the higher TBN values are designed to increase the operating period under harsh operating conditions, before the lubricant requires replacement.
But, can be there be a too high TBN?
For example, what could happen if a 10-15 TBN oil was used to lubricate a regular non-diesel car/motorcycle engine, instead of the standard 7-10 tbn one?