Lubricating oil composition for internal combustion engines

摘要

An internal combustion engine lubricating oil composition adapted for used with a maintenance-free system of engine and having excellent properties including oxidation stability, resistance against sludge formation and ability to clean the engine. The composition is characterized in that it comprises ingredients (A) through (D) below as essential components on the basis of total amount of composition and the total base number of the composition is between 2.0 and 6.0 mgKOH/g: (A) a specific alkaline earth metal type cleaning agent, (B) zinc dialkyldithiophosphate expressed by a specific general formula (1), (C) a succinic acid imide type ashless dispersant and (D) a phenol type and/or amine type ashless antioxidant.