Lubricant Composition Containing Viscosity Index Improver

Abstract

The disclosed invention relates to lubricant compositions containing viscosity index improvers in the form of polymers comprising structural units derived from ethylene, propylene and butylenes.

1 . A lubricant composition, comprising:
 at least about 60 percent by weight of an oil of lubricating viscosity;   a viscosity index improving amount of about 0.001 to about 2 percent by weight of a polymer comprising from about 5 mol % to about 20 mol % structural units derived from ethylene, from about 50 mol % to about 90 mol % structural units derived from propylene, and from about 5% to about 30 mol % structural units derived from butylene;   about 0.01 to about 20 percent by weight of a succinimide dispersant; and   about 0.05 to about 5 percent by weight of a detergent comprising an overbased calcium, magnesium, or sodium sulfonate wherein the sulfonate has a total base number in the range from about 250 to about 600.   
     
     
         2 . (canceled) 
     
     
         3 . The composition of  claim 1  wherein the viscosity index improving amount of the polymer is about 0.5 to about 2 percent by weight. 
     
     
         4 . The composition of  claim 1  wherein the dispersant comprises a polyisobutene substituted succinimide dispersant. 
     
     
         5 - 6 . (canceled) 
     
     
         7 . The composition of  claim 1  wherein the overbased sulfonate is present in an amount suitable to provide a TBN (total base number) in the range from about 1 to about 10 to the lubricant composition. 
     
     
         8 - 9 . (canceled) 
     
     
         10 . The composition of  claim 1  wherein the composition further comprises an antiwear agent. 
     
     
         11 . The composition of  claim 1  wherein the composition further comprises an antioxidant. 
     
     
         12 . The composition of  claim 1  wherein the composition further comprises a friction modifier. 
     
     
         13 . The composition of  claim 1  wherein the composition further comprises a pour point depressant. 
     
     
         14 . The composition of  claim 1  wherein the composition further comprises an anti-foam agent. 
     
     
         15 . The composition of  claim 1  wherein the composition further comprises one or more metal deactivators, additional supplemental viscosity modifiers, supplemental detergents, corrosion inhibitors, dispersant viscosity modifiers, extreme pressure agents, demulsifiers, seal swelling agents, or a mixture of two or more thereof. 
     
     
         16 . The composition of  claim 1  wherein the oil of lubricating viscosity comprises a Group II oil. 
     
     
         17 . The composition of  claim 1  wherein the oil of lubricating viscosity has a kinematic viscosity at 100° C. of less than about 5 cSt, and a viscosity index of less than about 130. 
     
     
         18 . The composition of  claim 1  wherein the polymer has a number average molecular weight in the range from about 10,000 to about 500,000. 
     
     
         19 . The composition of  claim 1  wherein the polymer has a Mw/Mn of about 4 or less. 
     
     
         20 . The composition of  claim 1  wherein the polymer comprises from about 5 to about 10 mol % structural units derived from ethylene, from about 60 to about 75 mol % structural units derived from propylene, from about 15 to about 30 mol % structural units derived from butylene, a number average molecular weight in the range from about 150,000 to about 250,000, and a Mw/Mn in the range from about 2 to about 2.5. 
     
     
         21 . The composition of  claim 1  wherein the composition has a sulfur content of about 1% by weight or less. 
     
     
         22 . The composition of  claim 1  wherein the composition has a phosphorus content of about 0.2% by weight or less. 
     
     
         23 . The composition of  claim 1  wherein the composition has a sulfated ash content in the range from about 0.3 to about 1.2% by weight. 
     
     
         24 . The composition of  claim 1  wherein the composition has a chlorine content of up to about 100 ppm. 
     
     
         25 . A method of lubricating an internal combustion engine, comprising: supplying to the engine the lubricant composition of  claim 1 . 
     
     
         26 - 27 . (canceled)