| abstract |
A lubricating oil composition which comprises a lube base oil comprising a mineral oil and/or synthetic oil and contains, as (A) an ash-free dispersant, an alkenyl- or alkylsuccinimide and/or a boron compound derivative thereof incorporated in the base oil in an amount of 0.01-0.14 mass% in terms of nitrogen amount based on the composition, the content of the alkenyl- or alkylsuccinic acid monoimide and/or boron compound derivative thereof in the ash-free dispersant being 0.05 mass% or lower in terms of nitrogen amount based on the composition. The composition further contains, as (B) an antioxidant, a dialkyldiphenylamine compound and a hindered phenol compound in amounts of 0.3-5.0 mass% and 0-2.5 mass%, respectively, based on the composition. The composition has (C) a sulfated ash content of 1.2 mass% or lower. The lubricating oil composition has excellent oxidative stability despite the low ash content and increases little in viscosity and acid value. It is suitable for use as a lubricating oil composition for internal combustion engines which is capable of prolonging the lubricating oil changing distance (time). |