Patent ID: 8076276

Claim:
A trunk piston marine engine lubricating oil composition for a medium-speed compression-ignited marine engine comprising, or made by admixing, an oil of lubricating viscosity, in a major amount, containing 50 mass % or more of a Group II basestock, and, in respective minor amounts, (A) an overbased metal hydrocarbyl-substituted hydroxybenzoate detergent having a basicity index of 5.5 or greater; and (B) an overbased metal hydrocarbyl-substituted hydroxybenzoate detergent having a basicity index of 2 or less, wherein the ratio of the mass of metal in detergent (A) to the mass of metal in detergent (B) is 10 or less; the trunk piston marine engine lubricating oil composition having a TBN (using ASTM D2896) of 20 to 60.