| abstract |
A lubricating oil composition for a natural gas engine and a method for preventing or suppressing the occurrence of an exhaust valve seat dent in a natural gas fuel internal combustion engine are provided. A natural gas engine lubricating oil composition comprising the following components is used: (a) a major amount of oil of lubricating viscosity, (b) one or more phosphorus-containing antiwear additives, (c) one (D) one or more alkyl-substituted hydroxyaromatic carboxylic acid alkaline earth metal salts, and (e) one or more antioxidants, provided that the natural gas engine lubricating oil composition is phosphorous. Is about 0.03 weight percent or less based on the total weight of the natural gas engine lubricating oil composition, and the natural gas engine lubricating oil composition is substantially free of any alkali metal-containing detergent. [Selection] Figure 1 |