Corrosion Inhibition

Abstract

The present invention provides a lubricating composition containing (a) an oil of lubricating viscosity; (b) a corrosion inhibitor; and (c) an antiwear agent comprising at least one of (i) polyhydric alcohol with oxyalkylene groups, (ii) a fatty amine, or (iii) mixtures thereof, wherein the lubricating composition has a total sulphated ash content of less than 0.8 wt %. The invention further provides for the use of the lubricating composition in an internal combustion engine.

1 . A lubricating composition comprising:
 (a) an oil of lubricating viscosity;   (b) an antiwear agent; and   (c) a polyhydric alcohol corrosion inhibitor comprising monomeric units of oxyalkylene groups,   wherein the lubricating composition has a total sulphated ash content of less than 0.8 wt %.   
   
   
       2 . The lubricating composition of  claim 1 , wherein the polyhydric alcohol contains 2 to 150 oxyalkylene groups. 
   
   
       3 . The lubricating composition of  claim 1 , wherein the oxyalkylene groups contain 3 or 4 carbon atoms. 
   
   
       4 . The lubricating composition of  claim 1 , wherein the corrosion inhibitor contains oxyalkylene groups with of 3 to 8 carbon atoms on at least 65 wt % of the oxyalkylene groups. 
   
   
       5 . The lubricating composition of  claim 1 , wherein the total sulphated ash content is 0.7 wt % or less. 
   
   
       6 . The lubricating composition of  claim 1 , wherein the composition has a phosphorus content of 900 ppm or less. 
   
   
       7 . The lubricating composition of  claim 1 , wherein the composition has a sulphur content of 50 ppm to 2000 ppm. 
   
   
       8 . The lubricating composition of  claim 1 , wherein the lubricating composition has a phosphorus content of 100 ppm to 700 ppm; and the lubricating composition has a sulphur content of less than 3000 ppm. 
   
   
       9 . The lubricating composition of  claim 1 , wherein the antiwear agent comprises a metal hydrocarbyl dithiophosphate. 
   
   
       10 . The lubricating composition of  claim 1  further comprising a viscosity modifier. 
   
   
       11 . The lubricating composition of  claim 10 , wherein the viscosity modifier includes at least one of styrene-butadiene rubbers, ethylene-propylene copolymers, hydrogenated styrene-isoprene polymers, hydrogenated isoprene polymers, polyalkyl styrenes, polyolefins, polyalkylmethacrylates and esters of maleic anhydride-styrene copolymers, or mixtures thereof. 
   
   
       12 . The lubricating composition of  claim 10 , wherein the viscosity modifier has a Mw of 20,000 to 300,000. 
   
   
       13 . The lubricating composition of  claim 1 , wherein the corrosion inhibitor is present from 0.01 to 10 weight percent of the lubricating composition. 
   
   
       14 . A method for lubricating an internal combustion engine, comprising supplying thereto a lubricant comprising the composition 1. 
   
   
       15 . (canceled)