Lubricating oil composition

Abstract

A lubricating oil composition including: a lubricating base oil; (A) a dispersant poly(meth)acrylate compound having a weight average molecular weight of 30,000 to 200,000 in an amount of 1 to 10 mass % on the basis of the total mass of the composition; and (B) a non-dispersant poly(meth)acrylate compound having a weight average molecular weight of 15,000 to 100,000 in an amount of no more than 15 mass % on the basis of the total mass of the composition, wherein the ratio MA/MB of the amount MA of the component (A) to the amount MB of the component (B) is 0.05 to 1; and the ratio MwB/MwA of the weight average molecular weight MwB of the component (B) to the weight average molecular weight MwA of the component (A) is 0.05 to 2.

1 . A lubricating oil composition comprising:
 a lubricating base oil;   (A) a dispersant poly(meth)acrylate compound having a weight average molecular weight of 30,000 to 200,000 in an amount of 1 to 10 mass % on the basis of the total mass of the composition; and   (B) a non-dispersant poly(meth)acrylate compound having a weight average molecular weight of 15,000 to 100,000 in an amount of no more than 15 mass % on the basis of the total mass of the composition,   wherein a ratio MA/MB of the amount MA of the component (A) to the amount MB of the component (B) is 0.05 to 1; and   a ratio MwB/MwA of the weight average molecular weight MwB of the component (B) to the weight average molecular weight MwA of the component (A) is 0.05 to 2.   
     
     
         2 . The lubricating oil composition according to  claim 1 ,
 the lubricating base oil consisting of: at least one Group II mineral base oil of API base stock categories, at least one Group III mineral base oil of API base stock categories, at least one Group IV synthetic base oil of API base stock categories, or at least one Group V synthetic base oil of API base stock categories, or any combination thereof,   wherein the lubricating base oil has a kinematic viscosity at 100° C. of 2.5 to 4.5 mm 2 /s.   
     
     
         3 . The lubricating oil composition according to  claim 1 ,
 wherein the lubricating oil composition has a kinematic viscosity at 100° C. of 4.5 to 7.5 mm 2 /s.   
     
     
         4 . The lubricating oil composition according to  claim 1 , further comprising:
 (C) a phosphorus-containing anti-wear agent in an amount of 200 to 1110 mass ppm in terms of phosphorus on the basis of the total mass of the composition.   
     
     
         5 . The lubricating oil composition according to  claim 1 , further comprising:
 (D) an overbased calcium detergent in an amount of 50 to 300 mass ppm in terms of calcium on the basis of the total mass of the composition.   
     
     
         6 . The lubricating oil composition according to  claim 5 ,
 the component (D) comprising an overbased calcium salicylate detergent in an amount of 50 to 300 mass ppm in terms of calcium on the basis of the total mass of the composition.   
     
     
         7 . The lubricating oil composition according to  claim 1 , further comprising:
 (E) a sulfur additive in an amount of 800 to 1300 mass ppm in terms of sulfur on the basis of the total mass of the composition.   
     
     
         8 . The lubricating oil composition according to  claim 1 , further comprising:
 (F) a compound comprising a C 10-24  chain aliphatic hydrocarbyl group and at least one functional group in an amount of 0.1 to 10.0 mass % on the basis of the total mass of the composition, the at least one functional group being selected from an amide bond, an imide bond, and an amino group.   
     
     
         9 . The lubricating oil composition according to  claim 1 , which is used in common for lubricating a wet clutch and lubricating a hypoid gear. 
     
     
         10 . A method for lubricating a wet clutch and a hypoid gear, the method comprising:
 supplying the lubricating oil composition as in  claim 1  to the wet clutch; and   supplying the lubricating oil composition to the hypoid gear,   wherein the lubricating oil composition is used in common for lubricating the wet clutch and lubricating the hypoid gear.