Patent ID: 8796192

Claim:
A natural gas engine lubricating oil composition comprising (a) a major amount of an oil of lubricating viscosity, (b) about 0.15 to about 1.5 wt. % of one or more phosphorus-containing anti-wear additives, wherein the one or more phosphorus-containing anti-wear additives comprises a zinc alkyldithiophosphate: (c) about 0.5 wt. % to about 1.5 wt. % of one or more oil soluble overbased alkaline earth metal-containing detergents comprising an oil soluble overbased calcium or magnesium phenate wherein the one or more oil soluble overbased alkaline earth metal-containing detergents have a base number (BN) of from greater than 50 to about 200; and (d) about 0.5 wt. % to about 2.0 wt. % of one or more oil soluble neutral alkali metal-containing detergents comprising an oil soluble neutral sodium or potassium sulfonate, wherein the natural gas engine lubricating oil composition contains no more than about 0.03 weight percent of phosphorus, based on the total weight of the natural gas engine lubricating oil composition; and wherein said lubricating oil composition has a sulfated ash content of no more than about 1 wt. % as determined by ASTM D 874.