Lubricant compositions

Abstract

Provided are lubricant compositions that exhibit high viscosity index and low Noack volatility. A lubricant composition of the invention comprises: (a) a polyalkylene glycol of formula I: RO-(AO) n -R 1 (I) wherein R, R 1 , and n are as defined herein; and (b) an additive package comprising an anti-oxidant.

What is claimed is: 
     
         1 . A lubricant composition comprising:
 (a) a polyalkylene glycol of formula I:
   RO—(AO) n —R 1   (I)
 
   wherein R is C 4 -C 22  alkyl; AO is independently ethyleneoxy, propyleneoxy, butyleneoxy, or mixtures of two or more thereof; n is 8-16; and R 1  is C 1 -C 6  alkyl; and   (b) an additive package comprising an amine anti-oxidant, wherein the lubricant composition has a Noack volatility of 13 percent or less and a viscosity index of at least 165.   
     
     
         2 . The lubricant composition according to  claim 1  wherein R is linear C 4 -C 14  alkyl 
     
     
         3 . The lubricant composition according to  claim 1  wherein R 1  is C 1 -C 3  alkyl. 
     
     
         4 . The lubricant composition according to  claim 1  wherein the polyalkylene glycol of formula I has a number average molecular weight of from 500 to 1500 g/mol. 
     
     
         5 . The lubricant composition according to  claim 1  having a viscosity index of at least 180. 
     
     
         6 . The lubricant composition according to  claim 1  wherein AO is a mixture of ethyleneoxy and propyleneoxy. 
     
     
         7 . The lubricant composition according to  claim 1  wherein AO is a mixture of propyleneoxy and butyleneoxy. 
     
     
         8 . The lubricant composition according to  claim 1  wherein AO is butyleneoxy. 
     
     
         9 . The lubricant composition according to  claim 1  wherein the polyalkylene glycol is of formula II:
   RO—(PO) n —R 1   (II)
 
 wherein R is C 4 -C 22  alkyl; PO is propyleneoxy; n is 8-16; and R 1  is C 1 -C 3  alkyl. 
 
     
     
         10 . The lubricant composition according to  claim 1  that the additive package further comprises:
 (i) an extreme pressure anti-wear additive, or 
 (ii) an anti-corrosion additive, or 
 (iii) a friction modifier, or 
 (iv) an acid scavenger, or 
 (v) any combination of (i)-(iv). 
 
     
     
         11 . The lubricant composition according to  claim 1  that is a motor oil. 
     
     
         12 . The lubricant composition according to  claim 11  wherein the motor oil is 0W-20 motor oil. 
     
     
         13 . A method of lubricating an internal combustion engine, comprising providing a lubricant composition according to  claim 1 .