Method Of Viscosity Control

Abstract

This invention relates to a method of lubricating an internal combustion engine comprising at least one of a crankcase, a gear and a wet-clutch, said method comprising supplying to said crankcase, gear and wet-clutch a lubricating composition comprising: (a) an oil of lubricating viscosity; and (b) a viscosity modifier with a number average molecular weight from 1000 to 75,000, wherein the lubricating composition has a SAE viscosity grade from XW—Y, wherein X is from 0 to 20 and Y is from 20 to 50; and wherein the lubricating composition has a phosphorus content from a metal hydrocarbyl dithiophosphate of 0.12 wt % or less.

1 . A method of lubricating an internal combustion engine comprising a crankcase and at least one of a gear and a wet-clutch, said method comprising supplying to said crankcase and to at least one of said gear and wet-clutch a lubricating composition comprising: 
 (a) an oil of lubricating viscosity; and    (b) a viscosity modifier with a number average molecular weight from about 1000 to about 75,000,    wherein the lubricating composition has a SAE viscosity grade from XW—Y, wherein X is from 0 to about 20 and Y is from about 20 to about 50; and wherein the lubricating composition has a phosphorus content from a metal hydrocarbyl dithiophosphate of 0.12 wt % or less.    
     
     
         2 . The method of  claim 1 , wherein the internal combustion engine has a common oil reservoir supplying the same lubricating composition to the crankcase and at least one of a gear and a wet-clutch.  
     
     
         3 . The method of  claim 1 , wherein the lubricating composition is supplied to the crankcase and to the gear (or multiplicity of gears).  
     
     
         4 . The method of  claim 1 , wherein the lubricating composition is supplied to the crankcase and the wet clutch.  
     
     
         5 . The method of  claim 1 , wherein the lubricating composition is supplied to the crankcase and both the gear (or gears) and the wet clutch.  
     
     
         6 . The method of  claim 1 , wherein the internal combustion engine is a 4-stroke engine.  
     
     
         7 . The method of  claim 6 , wherein the 4-stroke engine is a motorcycle engine.  
     
     
         8 . The method of  claim 1 , wherein the viscosity modifier includes at least one of: 
 (a) polyalkenes or a derivative thereof;    (b) polyalphaolefins;    (c) alpha-olefin-unsaturated carboxylic reagent copolymers;    (d) poly(meth)acrylates; 
 aromatic monomer and an unsaturated carboxylic acid or derivatives thereof; or  
   (f) mixtures thereof.    
     
     
         9 . The method of  claim 1 , wherein the viscosity modifier has a number average molecular weight 2000 to 60,000, or 8000 to 40,000.  
     
     
         10 . The method of  claim 1 , wherein the viscosity modifier has a number average molecular weight from 1000 to 20,000, or from 25,000 to 40,000.  
     
     
         11 . The method of  claim 1 , wherein the viscosity modifier is a poly(meth)acrylate.  
     
     
         12 . The method of  claim 11 , wherein the viscosity modifier is a functionalized poly(meth)acrylate.  
     
     
         13 . The method of  claim 12 , wherein the poly(meth)acrylate is functionalized with a nitrogen containing monomer.  
     
     
         14 . The method of  claim 1 , wherein the viscosity modifier is present from 0.5 wt % to 95 wt %, or from 1 wt % to 40 wt % of the lubricating composition.  
     
     
         15 . The method of  claim 1 , wherein the viscosity modifier has a Shear Stability Index (SSI) as determined by CEC L-45-A-99 of 22 or less.  
     
     
         16 . The method of  claim 1 , wherein the viscosity modifier has a Shear Stability Index (SSI) as determined by CEC L-45-A-99 of 4 to 18.