Lubricating oil composition, shock absorber, and method for using lubricating oil composition

Abstract

A lubricating oil composition may be used for lubrication of a shock absorber, and may include a base oil (A), a polyalkyl (meth)acrylate (B) having a weight average molecular weight in a range of from 150,000 to 900,000, and an olefin copolymer (C) having a weight average molecular weight of 100,000 or less.

1 . A lubricating oil composition suitable for lubrication of a shock absorber, the composition comprising:
 a base oil (A);   a polyalkyl (meth)acrylate (B) having a weight average molecular weight in a range of from 150,000 to 900,000; and   an olefin copolymer (C) having a weight average molecular weight of 100,000 or less.   
     
     
         2 . The composition of  claim 1 , wherein the polyalkyl (meth)acrylate (B) and the olefin copolymer (C), together, are present in is 20.0 mass % or less, based on total lubricating oil composition mass. 
     
     
         3 . The lubricating oil composition of  claim 1 , wherein a (B)/(C) mass content ratio of the polyalkyl (meth)acrylate (B) to the olefin copolymer (C) is in a range of from 1/99 to 90/10. 
     
     
         4 . The lubricating oil composition of  claim 1 , wherein the polyalkyl (meth)acrylate (B) is present in a range of from 0.1 to 10.0 mass %, based on total lubricating oil composition mass. 
     
     
         5 . The lubricating oil composition of  claim 1 , wherein the olefin copolymer (C) is present in a range of from 0.1 to 10.0 mass %, based on total lubricating oil composition mass. 
     
     
         6 . The lubricating oil composition of  claim 1 , wherein a weight average molecular weight of the olefin copolymer (C) is in a range of from 8,000 to 100,000. 
     
     
         7 . The lubricating oil composition of  claim 1 , wherein the olefin copolymer (C) comprises an ethylene propylene copolymer (C1). 
     
     
         8 . The composition of  claim 1 , wherein the components (A), polyalkyl (meth)acrylate (B), and the olefin copolymer (C), together, are present in a range of from 80 to 100 mass % based on the total amount of the lubricating oil composition. 
     
     
         9 . The lubricating oil composition of  claim 1 , having a BF viscosity at-40° C. is 1,500 m·Pas or less. 
     
     
         10 . A method of lubricating a shock absorber, the method comprising:
 applying the lubricating oil composition of  claim 1 , to the shock absorber.   
     
     
         11 . The composition of  claim 2 , wherein a (B)/(C) mass content ratio of the polyalkyl (meth)acrylate (B) to the olefin copolymer (C) is in a range of from 1/99 to 90/10. 
     
     
         12 . The composition of  claim 2 , wherein the polyalkyl (meth)acrylate (B) is present in a range of from 0.1 to 10.0 mass %, based on total lubricating oil composition mass. 
     
     
         13 . The composition of  claim 3 , wherein the polyalkyl (meth)acrylate (B) is present in a range of from 0.1 to 10.0 mass %, based on total lubricating oil composition mass. 
     
     
         14 . The composition of  claim 11 , wherein the polyalkyl (meth)acrylate (B) is present in a range of from 0.1 to 10.0 mass %, based on total lubricating oil composition mass. 
     
     
         15 . The composition of  claim 14 , wherein the olefin copolymer (C) is present in a range of from 0.1 to 10.0 mass %, based on total lubricating oil composition mass.