a lubricating oil with very low phosphorus content , and having long life as evidenced by a reduction in viscosity increase , oxidation and nitration , comprises a major amount of a base oil of lubricating viscosity and a minor amount of a mixture of neutral and overbased metallic detergents , at least a zinc dialkyldithiocarbamate antiwear additive and at least a dihydrocarbylthiocarbamoyl .