Friction reducing method for lubricating oil compositions and gasoline engines for internal combustion engines

From low temperature region that assumes at the start of the engine, in a practical temperature range above 80 ° C., to provide an internal combustion machine lubricating oil composition which can exhibit sufficient friction reducing effect. It has an alkylene oxide to structural unit, and the surfactant is below HLB value of 7 or more 15, and the internal combustion engine lubricating oil composition comprising a lubricating base oil.