EXTENDED DRAIN DIESEL LUBRICANT FORMULATIONS

摘要

A method for maintaining a total base number (TBN) above about 3 mg KOH/g for a lubricant for a diesel engine for greater than about 184 days. The method includes supplying as the lubricant, a lubricant composition comprising a sulfonate detergent having a TBN ranging from about 20 to about 100 and a phenate detergent having a TBN ranging from about 200 to about 350 and an antioxidant selected from the group consisting essentially of hindered phenolic derivatives of C3 to C6 acids and C7 to C9 esters of hindered phenolic derivatives of C3 to C6 acids. The phenate detergent is present in an amount that is greater than 15 percent by weight of the total weight of detergents in the lubricant composition and the lubricant composition is substantially devoid of zinc dialkydithiophosphate compounds and has a sulfated ash content of less than 1.0 wt. %.