Lubricant compositions for direct injection engines

Abstract

The disclosed technology provides a lubricating composition and a method of lubricating an internal combustion engine where the lubricating composition contains an oil of lubricating viscosity, one or more metal-containing, sulfur-free, alkyl-phenol based detergents, an alkaline earth metal sulfonate detergent, a polyisobutenyl succinimide dispersant, and a dispersant viscosity modifier having a number average molecular weight of at least 20,000. The lubricating composition of the present invention can be formulated to have lower HTHS viscosity, and reduced phosphorous content, while providing protection against adhesive wear.

1 . A low viscosity lubricating composition, comprising:
 a) an oil of lubricating viscosity;   b) one or more metal-containing sulfur-free alkyl-phenol based detergents derived from an alkylphenol in an amount to deliver at least 0.2 weight percent alkylphenol-containing soap to the composition;   c) one or more alkaline earth metal sulfonate detergents in an amount to deliver at least 0.8% by weight sulfonate soap to the composition; and   d) 1 wt % to 4.5 wt % of one or more polyisobutylene succinimide dispersants;   e) 0.1 wt % to 1.2 wt % of a dispersant viscosity modifier derived from a polyolefin having a number average molecular weight of at least 20,000;   
       wherein the lubricating composition contains less than 0.2 wt % of a sulfur-coupled phenate detergent. 
     
     
         2 . The composition of  claim 1  wherein the lubricating composition contains less than 0.15 wt % of a sulfur-coupled phenate detergent. 
     
     
         3 . The composition of  claim 2  wherein the composition is substantially free of sulfur-coupled phenate detergents. 
     
     
         5 . The composition of  claim 1  wherein the dispersant viscosity modifier comprises a mixture of at least one low molecular weight dispersant viscosity modifier, derived from a polyolefin having a number average molecular weight of less than 20,000, and at least one high molecular weight dispersant viscosity modifier, derived from a polyolefin having a number average molecular weight of at least 40,000. 
     
     
         6 . The composition of  claim 5  wherein the at least one low molecular weight dispersant viscosity modifier is derived from a polyolefin having a number average molecular weight of 10,000 or lower. 
     
     
         7 . The composition of  claim 5  wherein the at least one high molecular weight dispersant viscosity modifier is derived from a polyolefin having a number average molecular weight of at least 45,000. 
     
     
         8 . The composition of  claim 1  wherein the sulfur-free alkylphenol-based detergent is selected from alkylene coupled alkylphenol detergents, alkyl salicylate detergents, and combinations thereof. 
     
     
         9 . The composition of  claim 8  wherein the sulfur-free alkylphenol-based detergent comprises Mg saligenin. 
     
     
         10 . The composition of  claim 8  wherein the sulfur-free alkylphenol-based detergent comprises Ca salixarate. 
     
     
         11 . The composition of  claim 1  further comprising:
 a metal dialkyl dithiophosphate, wherein about 65 mol % of the alkyl groups have 5 or more carbon atoms, present in an amount to deliver 0.01 to 0.08 weight percent phosphorus to the composition. 
 
     
     
         12 . The composition of  claim 1  further comprising:
 a metal dialkyl dithiophosphate, wherein about 75 mol % of the alkyl groups have 5 or more carbon atoms, present in an amount to deliver 0.01 to 0.08 weight percent phosphorus to the composition and wherein the composition comprises 1 wt % to 4 wt % of one or more polyisobutylene succinimide dispersants. 
 
     
     
         13 . The composition of  claim 1  wherein the lubricating composition is a high temperature high shear fluid having a dynamic viscosity of less than 3.05 at 150° C. 
     
     
         14 . The composition of  claim 1  wherein the lubricating composition has a viscosity of 10 centistokes or lower at 100° C. 
     
     
         15 . A method of lubricating a compression ignition internal combustion engine comprising supplying to the engine a low phosphorus lubricant composition comprising:
 a) an oil of lubricating viscosity;   b) one or more metal-containing sulfur-free alkyl-phenol based detergents in an amount to deliver at least 0.2 weight percent alkylphenol-containing soap to the composition;   c) one or more alkaline earth metal sulfonate detergents in an amount to deliver at least 0.8% by weight sulfonate soap to the composition;   d) 1 wt % to 4.5 wt % of one or more polyisobutylene succinimide dispersants;   e) 0.1 wt % to 1.2 wt % of a dispersant viscosity modifier derived from polyolefin having a number average molecular weight of at least 20,000;   
       wherein the composition contains less than 0.2 weight percent of a sulfur-coupled phenate detergent. 
     
     
         16 . The method of  claim 15  wherein the lubricating composition comprises less than 0.15 wt % of a sulfur-coupled phenate detergent. 
     
     
         17 . The method of  claim 15  wherein the dispersant viscosity modifier comprises a mixture of at least one low molecular weight dispersant viscosity modifier, derived from a polyolefin having a number average molecular weight less than 20,000, and at least one high molecular weight dispersant viscosity modifier, derived from a polyolefin having a number average molecular weight of at least 40,000. 
     
     
         18 . The method of  claim 17  wherein the at least one low molecular weight dispersant viscosity modifier is derived from a polyolefin having a number average molecular weight of 10,000 or lower. 
     
     
         19 . The method of  claim 18  wherein the at least one high molecular weight dispersant viscosity modifier is derived from a polyolefin having a number average molecular weight of at least 45,000. 
     
     
         20 . The method of  claim 15  wherein the sulfur-free alkylphenol-based detergent is selected from alkylene coupled alkylphenol detergents, alkylsalicylate detergents, and combinations thereof. 
     
     
         21 . The method of  claim 20  wherein the sulfur-free alkylphenol-based detergent comprises Mg saligenin. 
     
     
         22 . The method of  claim 20  wherein the sulfur-free alkylphenol-based detergent comprises Ca salixarate. 
     
     
         23 . The method of  claim 15  further comprising:
 a metal dialkyl dithiophosphate, wherein at least about 65 mol % of the alkyl groups have 5 or more carbon atoms, present in an amount to deliver 0.01 to 0.08 weight percent phosphorus to the composition. 
 
     
     
         24 . The method of  claim 15  further comprising:
 a metal dialkyl dithiophosphate, wherein at least about 75 mol % of the alkyl groups have 5 or more carbon atoms, present in an amount to deliver 0.01 to 0.08 weight percent phosphorus to the composition and wherein the composition comprises 1 wt % to 4 wt % of one or more polyisobutylene succinimide dispersants. 
 
     
     
         25 . The method of  claim 15  wherein the lubricating composition is a high temperature high shear fluid having a dynamic viscosity of less than 3.05 at 150° C. 
     
     
         26 . The method of  claim 15  wherein the lubricating composition has a viscosity of 10 centistokes or lower at 100° C. 
     
     
         27 . A method of reducing adhesive wear in a compression engine lubricated with a low phosphorus lubricant composition, comprising supplying to the engine a lubricant composition comprising:
 a) an oil of lubricating viscosity;   b) one or more metal-containing sulfur-free detergents derived from an alkylphenol in an amount to deliver at least 0.2 weight percent alkylphenol-containing soap to the composition;   c) one or more alkaline earth metal sulfonate detergents in an amount to deliver at least 0.8% by weight sulfonate soap to the composition;   d) 1 wt % to 4.5 wt % of one or more polyisobutylene succinimide dispersants; and   e) 0.1 wt % to 1.2 wt % of a dispersant viscosity modifier derived from polyolefin having a number average molecular weight of at least 20,000;   wherein the lubricant composition contains less than 0.2 weight percent of a sulfur-coupled phenate detergent.   
     
     
         28 . The method of  claim 27  wherein the lubricating composition comprises less than 0.15 wt % of a sulfur-coupled phenate detergent. 
     
     
         29 . The method of  claim 27  wherein the dispersant viscosity modifier comprises a mixture of at least one low molecular weight dispersant viscosity modifier, derived from a polyolefin having a number average molecular weight of less than 20,000, and at least one high molecular weight dispersant viscosity modifier, derived from a polyolefin having a number average molecular weight of at least 40,000. 
     
     
         30 . The method of  claim 29  wherein the at least one low molecular weight dispersant viscosity modifier is derived from a polyolefin having a number average molecular weight of 10,000 or lower. 
     
     
         31 . The method of  claim 29  wherein the at least one high molecular weight dispersant viscosity modifier is derived from a polyolefin having a number average molecular weight of at least 45,000. 
     
     
         32 . The method of  claim 27  wherein the sulfur-free alkylphenol-based detergent is selected from alkylene coupled alkylphenol detergents, alkylsalicylate detergents, and combinations thereof. 
     
     
         33 . The method of  claim 32  wherein the sulfur-free alkylphenol-based detergent comprises Mg saligenin. 
     
     
         34 . The method of  claim 32  wherein the sulfur-free alkylphenol-based detergent comprises Ca salixarate. 
     
     
         35 . The method of  claim 27  further comprising:
 a metal dialkyl dithiophosphate, wherein at least about 65 mol % of the alkyl groups have 5 or more carbon atoms, present in an amount to deliver 0.01 to 0.08 weight percent phosphorus to the composition. 
 
     
     
         36 . The method of  claim 27  further comprising:
 a metal dialkyl dithiophosphate, wherein at least about 75 mol % of the alkyl groups have 5 or more carbon atoms, present in an amount to deliver 0.01 to 0.08 weight percent phosphorus to the composition and wherein the composition comprises 1 wt % to 4 wt % of one or more polyisobutylene succinimide dispersants. 
 
     
     
         37 . The method of  claim 27  wherein the lubricating composition is a high temperature high shear fluid having a dynamic viscosity of less than 3.05 at 150° C. 
     
     
         38 . The method of  claim 27  wherein the lubricating composition has a viscosity of 10 centistokes or lower at 100° C.