Lubricating oil composition

Abstract

A lubricating oil composition is provided containing a base oil having a kinematic viscosity at 40° C. in the range of from 2 to 20 mm 2 /s and a viscosity index of 50 or more and a polymethacrylate, wherein the lubricating oil composition has a kinematic viscosity at 40° C. in the range of from 22 to 95 mm 2 /s; a kinematic viscosity at 100° C. in the range of from 10 to 30 mm 2 /s; a pour point of −10° C. or less; a CCS viscosity at −20 ° C. of 2500 mPas or less; and a flash point of 140° C. or more.

1 . A lubricating oil composition comprising a base oil having a kinematic viscosity at 40° C. in the range of from 2 to 20 mm 2 /s and a viscosity index of 50 or more and a polymethacrylate, 
 wherein the lubricating oil composition has a kinematic viscosity at 40° C. in the range of from 22 to 95 mm 2 /s; a kinematic viscosity at 100° C. in the range of from 10 to 30 mm 2 /s;    a pour point of −10° C. or less;    a CCS viscosity at −20° C. of 2500 mPas or less; and    a flash point of 140° C. or more.    
   
   
       2 . The lubricating oil composition of  claim 1  wherein the weight average molecular weight of the polymethacrylate is in the range of from 150,000 to 700,000.  
   
   
       3 . The lubricating oil composition of  claim 2  wherein the weight average molecular weight of the polymethacrylate is in the range of from 200,000 to 500,000.  
   
   
       4 . The lubricating oil composition of  claim 1  wherein the viscosity index of the base oil is 70 or more.  
   
   
       5 . The lubricating oil composition of  claim 1  wherein the lubricating oil composition further comprises at least one type of additive selected from an anti-wear agent, an antioxidant, an anti-rust agent, a corrosion inhibitor and an antifoaming agent.  
   
   
       6 . The lubricating oil composition of  claim 1  wherein said lubricating oil composition is a hydraulic oil composition for a door closer or a hydraulic oil composition for a floor hinge or both.  
   
   
       7 . The lubricating oil composition of  claim 2  wherein the viscosity index of the base oil is 70 or more.  
   
   
       8 . The lubricating oil composition of  claim 7  wherein the lubricating oil composition further comprises at least one type of additive selected from an anti-wear agent, an antioxidant, an anti-rust agent, a corrosion inhibitor and an antifoaming agent.  
   
   
       9 . The lubricating oil composition of  claim 5  wherein said lubricating oil composition is a hydraulic oil composition for a door closer or a hydraulic oil composition for a floor hinge or both.  
   
   
       10 . A method of lubricating a door closer or a floor hinge comprising using a lubricating oil composition of  claim 1  to lubricate said door closer or floor hinge.  
   
   
       11 . A method of lubricating a door closer or a floor hinge comprising using a lubricating oil composition of  claim 2  to lubricate said door closer or floor hinge.  
   
   
       12 . A method of lubricating a door closer or a floor hinge comprising using a lubricating oil composition of  claim 4  to lubricate said door closer or floor hinge.  
   
   
       13 . A method of lubricating a door closer or a floor hinge comprising using a lubricating oil composition of  claim 7  to lubricate said door closer or floor hinge.  
   
   
       14 . A method of lubricating a door closer or a floor hinge comprising using a lubricating oil composition of  claim 8  to lubricate said door closer or floor hinge.