METHOD OF LUBRICATING AN INTERNAL COMBUSTION ENGINE AND IMPROVING THE EFFICIENCY OF THE EMISSIONS CONTROL SYSTEM OF THE ENGINE

摘要

Internal combustion engines exhibit improved efficiency of the emissions control system by using a lubricating oil composition of a base oil, an alkali or alkaline earth metal-containing detergent; a metal salt of one or more phosphorus-containing compounds represented by the formula (I) , wherein X1 and X2 are independently O or S, and R1 and R2 are independently hydrocarbyl groups, the average total number of carbon atoms in R1 and R2 for the one or more phosphorus-containing compounds being at least 10.4; and an acylated nitrogen-containing compound having at least about 10 alphatic carbon atoms and a TBN of at least about 2; the lubricating oil composition being characterized by a phosphorus concentration of up to about 0.12% by weight and the substantial absence of copper, thereby generating a lean-phosphorus containing exhaust gas.