A method of reducing the rate of decrease of the basicity of a lubricating oil composition used in an engine

摘要

A method is disclosed for reducing the rate of decrease of basicity (determined according to ASTM D2896) in a lubricating oil composition used in an engine. The lubricating oil composition includes at least one overbased alkali or alkaline earth metal detergent. In the process, the lubricating oil composition will be one or more compounds of the formula (I): in which x is from 1 to 50, preferably from 1 to 40, especially from 1 to 30; R1 and R2 are H, hydrocarbon groups of 1 to 12 carbon atoms or hydrocarbon groups of 1 to 12 carbon atoms and at least one heteroatom; R is a hydrocarbon group having 9 to 100, preferably 9 to 70, most preferably 9 to 50 carbon atoms; and n is 0 to 10, or alkaline earth metal salts thereof are added. The compounds of the formula (I) are preferably methylene-bridged alkylphenols or ethoxylated methylene-bridged alkylphenols.