METHOD OF REDUCING RATE OF DEPLETION OF BASICITY OF LUBRICATING OIL COMPOSITION IN ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a method of reducing the rate of depletion of basicity of a lubricating oil composition in use in an engine for marine cylinder, trunk piston engine, gas engine, crankcase or the like.SOLUTION: A lubricating oil composition includes at least one overbased alkali metal or alkaline earth metal detergent expressed as follows. One or more compounds or its alkaline earth metal salt are/is added. The compounds of formula (I) are preferably methylene-bridged alkyl phenols or ethoxylated methylene-bridged alkyl phenols.