TBN Number and ULSD
Posted by Alex from portland, ME, US on April 6, 2007
Has the significance of a high TBN number been affected by the introduction of ULSD?
TBN is a measure to determine the engine oils ability to withstand attack from corrosive components (Acids) formed by combustion of the diesel, a higher TBN means better protection from corrosion
There are two types of acids that are formed in the combustion of an engine, sulfuric acid from the sulfur in the fuel and nitric acid from the NOX. ULSD has seen a dramatic reduction of sulfur in the fuel, which should result in reduced sulfuric acid; however EGR rates have increased dramatically which will result in higher nitric acid components. The decrease from ULSD is smaller than the increase from EGR, resulting in TBN being as important now as ever.
