Patent ID: 8071517

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 4.5 or less; and (B) an overbased metal hydrocarbyl-substituted hydroxybenzoate detergent having a basicity index of greater than 4.5, wherein the ratio of detergent (A) to detergent (B), both expressed as mass of active ingredient, is in the range from 0.5 to 15; the trunk piston marine engine lubricating oil composition having a TBN (using ASTM D2896) of 20 to 60.