| abstract |
Providing a lubricating oil composition for internal combustion engines which has high resistance to oxidation by nitrogen oxides, excellent friction characteristics that is maintained for a prolonged period, and reduces the fuel consumption for a prolonged period. A lubricating oil composition for internal combustion engines is provided consisting of a base oil principally consisting of a hydrocarbon oil which has a dynamic viscosity of 2-20 mm2/s at 100°C and contains 3 wt% or less aromatic components in total, 45 wt% or more one- and two-ring naphthenes in total, 50 wt ppm or less sulfur and 50 wt ppm or less nitrogen, to which are added, with respect to the total weight of the composition, 0.02-0.2 wt% as molybdenum of molybdenum dithiocarbamate, 0.02-0.15 wt% as phosphorus of zinc dithiophosphate, and 0.05-3 wt% of phenol-based antioxidant. The lubricating oil composition according to the invention has a low friction coefficient, which is maintained for a prolonged period even after oxidation by nitrogen oxides. |