To provide a lubricating oil composition capable of suppressing abrasion due to soot mixing which becomes remarkable when the content of a phosphorus compound such as ZnDTP (a zinc dialkyldithiophosphate) is reduced and suitable for diesel engine oil or direct injecting gasoline engine oil achieving a longer life such as performances of maintaining base number and mitigating effects on an exhaust gas post-processing device.
The lubricating oil composition is characterized in that the composition comprises (A) a viscosity index improver having 1-50 PSSI (permanent shear stability index) based on the total amounts of the composition in a lubricating base oil. (A) The viscosity index improver comprises (A1) a polymethacrylate-based viscosity index improver having a polar group in an amount of 0.1-20 mass% based on the total amount of the composition, (B) a phosphorus-containing abrasion inhibitor in an amount of 0.01-0.09 mass% in terms of the amount of phosphorus based on the total amount of the composition, (C) a salicylate-based cleaner in an amount of 0.01-1 mass% in terms of the amount of a metal based on the total amount of the composition and (D) an organomolybdenum compound in an amount of 0.001-0.2 mass% in terms of the amount of molybdenum (Mo) based on the total amount of the composition. The sulfur content in the composition is 0.3 mass%.
Hoshino, Koji
Takeshima, Shigeki
| WO2005123887A1 |