Engine Lubricants Containing a Polyether

Abstract

A sump-lubricated, spark-ignited engine is lubricated by supplying thereto a lubricant which comprises (a) an oil of lubricating viscosity; (b) a polyether; and (c) a metal-containing detergent. The lubricant has a total phosphorus content of less than 0.075 percent by weight.

What is claimed is: 
     
         1 . A method for lubricating a sump-lubricated, spark-ignited engine, comprising supplying to said engine a lubricant which comprises:
 (a) an oil of lubricating viscosity;   (b) about 0.1 to about 5 percent by weight of a polyether represented by the formula
   R 1 —(—O—R 2 —) n —OR 3  
 
   
       wherein R 1  is a hydrocarbyl group of 1 to about 50 carbon atoms, each R 2  is independently an alkylene group of 2 to 4 carbon atoms, n is 2 to about 50, and R 3  is H or a group of the structure —CH 2 CH 2 CH 2 NH 2 ; and
 (c) a metal-containing detergent, comprising a salicylate detergent having a total base number of about 120 to about 400 (oil free basis), said salicylate detergent being present at about 0.3 to about 1.5 percent by weight of said lubricant; 
 said lubricant having a total phosphorus content of less than 0.075 percent by weight; 
 and wherein the lubricant comprises a zinc dihydrocarbyldithiophosphate in an amount to contribute about 0.005 to about 0.075 weight percent phosphorus. 
 
     
     
         2 . The method of  claim 1  wherein the polyether comprises a reaction product of one unit derived from a hydroxy-containing hydrocarbon and two or more units derived from an alkylene oxide, wherein the hydroxy-containing hydrocarbon contains 1 to about 50 carbon atoms and the alkylene group of the alkylene oxide contains 2 to 4 carbon atoms, wherein the reaction product is optionally further reacted with acrylonitrile and hydrogenated to provide a terminal amino group. 
     
     
         3 . The method of  claim 1  wherein the polyether comprises a polyetheramine. 
     
     
         4 . The method of  claim 1  wherein the salicylate detergent comprises an overbased calcium hydrocarbyl-substituted salicylate detergent. 
     
     
         5 . The method of  claim 1  wherein the amount of the detergent is about 0.05 to about 1.5 percent by weight. 
     
     
         6 . The method of  claim 1  wherein the zinc dihydrocarbyldithiophosphate is present in an amount to contribute about 0.01 to about 0.06 weight percent phosphorus. 
     
     
         7 . The method of  claim 1  wherein the phosphorus content of the lubricant is about 0.01 to about 0.05 percent by weight. 
     
     
         8 . The method of  claim 1  wherein the sulfated ash level of the lubricant is less than about 0.80 percent. 
     
     
         9 . The method of  claim 1  wherein the lubricant further comprises an ashless antioxidant. 
     
     
         10 . A lubricant comprising
 (a) an oil of lubricating viscosity;   (b) about 0.1 to about 5 percent by weight of a polyether represented by the formula
   R 1 —(—O—R 2 —) n —OR 3  
 
   
       wherein R 1  is a hydrocarbyl group of 1 to about 50 carbon atoms, each R 2  is independently an alkylene group of 2 to 4 carbon atoms, n is 2 to about 50, and R 3  is H or a group of the structure —CH 2 CH 2 CH 2 NH 2  and
 (c) a metal-containing detergent, comprising a salicylate detergent having a total base number of about 120 to about 400 (oil free basis), said salicylate detergent being present at about 0.3 to about 1.5 percent by weight of said lubricant; 
 said lubricant having a total phosphorus content of less than about 0.075 percent by weight, 
 and wherein the lubricant comprises a zinc dihydrocarbyldithiophosphate in an amount to contribute about 0.005 to about 0.075 weight percent phosphorus. 
 
     
     
         11 . The lubricant of  claim 10  wherein the polyether comprises a reaction product of one unit of a hydroxy-containing hydrocarbon and two or more units of an alkylene oxide, wherein the hydroxy-containing hydrocarbon contains 1 to 50 carbon atoms and the alkylene group of the alkylene oxide contains 2 to 4 carbon atoms, wherein the reaction product is optionally further reacted with acrylonitrile and hydrogenated to provide a terminal amino group. 
     
     
         12 . The lubricant of  claim 10  wherein the polyether is present in an amount of about 0.5 to about 3 percent by weight. 
     
     
         13 . The lubricant of  claim 10  wherein the metal-containing detergent comprises an overbased calcium hydrocarbyl-substituted salicylate detergent. 
     
     
         14 . A composition prepared by admixing the components of  claim 10 .