Lubricating Oil Composition For Automoblie Engine Lubrication.

Abstract

Provided is a lubricating oil composition that is highly fuel-efficient and has high wear resistance and is particularly suited for lubrication of a motorcycle four-cycle gasoline engine or a diesel engine vehicle having an exhaust gas after-treatment device. The lubricating oil composition, which is a lubricating oil composition having an SAE viscosity grade of 5W20, comprises a base oil and predetermined amounts of additive components comprising of a nitrogen-containing ash-free dispersant, an alkali earth metal-containing detergent, a phosphorus-containing anti-wear agent, an antioxidant, and a viscosity index-improving agent, wherein the viscosity index is within a range of 140 to 230, the high-shear viscosity at 150° C. is 2.9 mPa·s or higher, and the NOACK evaporation loss is 13% or less.

What is claimed is: 
     
         1 . A lubricating oil composition for automobile engine lubrication, which is a lubricating oil composition comprising a base oil having an SAE viscosity grade of 5W20, wherein the viscosity index is within a range of 140 to 230, the high-shear viscosity at 150° C. is 2.9 mPa·s or higher, and the NOACK evaporation loss is 13% or less, further comprising:
 a) a nitrogen-containing ash-free dispersant at 0.01 to 0.3 mass % in terms of the nitrogen content, 
 b) an alkaline earth metal-containing detergent at 0.08 to 0.4 mass % in terms of alkaline earth metal content, 
 c) a phosphorus-containing anti-wear agent at 0.05 to 0.12 wt % in terms of phosphorus content, 
 d) an antioxidant selected from the group consisting of amine compounds, phenol compounds, and molybdenum compounds at 0.1 to 7 mass %, 
 e) a viscosity index-improving agent at 0.5 to 20 mass %, and further wherein the amount of each additive component is the mass % in terms of the total amount of lubricating oil composition. 
 
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the dynamic viscosity at 100° C. is within a range of 8.5 mm 2 /s or greater, but less than 9.3 mm 2 /s. 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the base oil comprises as a base oil component at least 80 mass % of a mineral oil base oil having a dynamic viscosity at 100° C. that is within a range of 2 to 9 mm 2 /s and a viscosity index of 133 to 160. 
     
     
         4 . The lubricating oil composition according to  claim 3 , wherein the base oil is a mineral oil having a dynamic viscosity at 100° C. that is within a range of 2 to 9 mm 2 /s and a viscosity index of 133 to 160. 
     
     
         5 . The lubricating oil composition according to  claim 1 , wherein the base oil is a base oil having a viscosity index of 133 to 160 that is obtained by hydrogenation and isomerization of either a slack wax or a synthetic wax produced by the Fischer-Tropsch method and then distillation and dewaxing treatment. 
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein the viscosity index-improving agent is a polymethacrylate polymer having a shear stability index of 30 or less. 
     
     
         7 . The lubricating oil composition according to  claim 1 , which further comprises an organic sulfur compound as an additive component. 
     
     
         8 . The lubricating oil composition according to  claim 1 , which is for lubrication of a motorcycle four-cycle gasoline engine. 
     
     
         9 . The lubricating oil composition according to  claim 1 , which is for lubricating the engine of a diesel engine vehicle having an exhaust gas after-treatment device. 
     
     
         10 . A method for lubricating a motorcycle four-cycle gasoline engine using the lubricating oil composition according to  claim 1 . 
     
     
         11 . A method for lubricating an engine of a diesel engine vehicle having an exhaust gas after-treatment device using the lubricating oil composition according to  claim 1 .