Method for improving engine fuel efficiency

Abstract

A method for improving fuel efficiency and reducing frictional properties while maintaining or improving deposit control, in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition including a lubricating oil base stock as a major component, and a friction modifier mixture as a minor component. Fuel efficiency and frictional properties are improved and deposit control is maintained or improved as compared to frictional properties and deposit control achieved using a lubricating engine oil containing a minor component other than the friction modifier mixture. A lubricating engine oil having a composition including a lubricating oil base stock as a major component, and a friction modifier mixture as a minor component. The lubricating engine oils are useful in internal combustion engines including direct injection, gasoline and diesel engines.

What is claimed is: 
     
         1 . A method fur improving fuel efficiency and reducing frictional properties, while maintaining or improving deposit control, in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil, said formulated oil having a composition comprising a lubricating oil base stock as a major component; and a friction modifier mixture comprising a first friction modifier, and at least one other friction modifier different from said first friction modifier, as a minor component; wherein said first friction modifier and said at least one other friction modifier are selected from the group consisting of an alkoxylated fatty acid ester, alkanolamide, glycerol fatty acid ester, borated glycerol fatty acid ester, and fatty alcohol ether; and wherein fuel efficiency and friction reduction properties are improved and deposit control is maintained or improved as compared to friction reduction properties and deposit control achieved using a lubricating engine oil containing a minor component other than the friction modifier mixture. 
     
     
         2 . The method of  claim 1  wherein the lubricating oil base stock comprises a. Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         3 . The method of  claim 1  wherein, in comparison with fuel efficiency achieved using a lubricating engine oil containing a minor component other than the friction modifier mixture, the lubricating engine oil containing the friction modifier mixture exhibits a fuel efficiency, FEI sum, greater than 1.1×, as determined by a Sequence VID Fuel Economy (ASTM D7589) engine test. 
     
     
         4 . The method of  claim 4  wherein the alkoxylated fatty acid ester is selected from polyoxyethylene stearate and fatty acid polyglycol ester; the alkanolamide is selected from lauric acid diethylalkanolamide and palmic acid diethylalkanolamide; the glycerol fatty acid ester is selected from mixed glyceride ester and glycerol mono-stearate; the borated glycerol fatty acid ester is selected from borated mixed glyceride ester and borated glycerol mono-sterate; and the fatty alcohol ether is selected from stearyl ether and myristyl ether. 
     
     
         5 . The method of  claim 1  wherein the friction modifier mixture comprises an ethoxylated fatty acid ester and a glycerol fatty acid ester. 
     
     
         6 . The method of  claim 1  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV and/or Group V base oil the friction modifier mixture comprises an ethoxylated fatty acid ester and a glycerol fatty acid ester. 
     
     
         7 . The method of  claim 1  wherein the weight ratio of the first friction modifier to the other friction modifier is from 0.1:1 to 1:0.1. 
     
     
         8 . The method of  claim 1  wherein the lubricating oil base stock is present in an amount of from 70 weight percent to 95 weight percent, and the friction modifier mixture is present in an amount of from 0.01 weight percent to 2.5 weight percent, based on the total, weight of the formulated oil. 
     
     
         9 . The method of  claim 1  wherein the lubricating oil base stock is present in an amount of from 70 weight percent to 95 weight percent, and the friction modifier mixture is present in an amount of from 0.01 weight percent to 1.0 weight percent, based on the total weight of the formulated oil. 
     
     
         10 . The method of  claim 1  wherein the lubricating oil further comprises one or more of an anti-wear additive, viscosity index improver, antioxidant, detergent, dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, anti-rust additive, and organic metallic friction modifier. 
     
     
         11 . The method of  claim 1  wherein, in friction measurements of the lubricating oil by mini-traction machine (MTM) in Stribeck mode at 140° C., the integrated Stribeck friction coefficient of the lubricating oil in the MTM is reduced as compared to the integrated Stribeck friction coefficient of a lubricating oil containing a minor component other than the friction modifier mixture; and wherein, in deposit measurements of the lubricating oil by thermo-oxidation engine oil simulation TEOST 33C, the amount of total deposits is reduced or maintained as compared to the amount of total deposits in a lubricating oil containing a minor component other than the friction modifier mixture. 
     
     
         12 . A lubricating engine oil having a composition comprising a lubricating oil base stock as a major component; and a friction modifier mixture comprising a first friction modifier, and at least one other friction modifier different from said first friction modifier, as a minor component; wherein said first friction modifier and said at least one other friction modifier are selected from the group consisting of an alkoxylated fatty acid ester, alkanolamide, glycerol fatty acid ester, borated glycerol fatty acid ester, and fatty alcohol ether; and wherein fuel efficiency and friction reduction properties are improved and deposit control is maintained or improved as compared to friction reduction properties and deposit control achieved using a lubricating engine oil containing a minor component other than the friction modifier mixture. 
     
     
         13 . The lubricating engine oil of  claim 12  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         14 . The lubricating engine oil of  claim 12  wherein, in comparison with fuel efficiency achieved using a lubricating engine oil containing a minor component other than the friction modifier mixture, the lubricating engine oil containing the friction modifier mixture exhibits a fuel efficiency, FEI sum, greater than 1.1×, as determined by a Sequence VID Fuel Economy (ASTM D7589) engine test. 
     
     
         15 . The lubricating engine oil of  claim 12  wherein the alkoxylated fatty acid ester is selected from polyoxyethylene stearate and fatty acid polyglycol ester; the alkanolamide is selected from lauric acid diethylalkanolamide and palmic acid diethylalkanolamide; the glycerol fatty acid ester is selected from mixed glyceride ester and glycerol mono-stearate; the borated glycerol fatty acid ester is selected from borated mixed glyceride ester and borated glycerol mono-sterate; and the fatty alcohol ether is selected from stearyl ether and myristyl ether. 
     
     
         16 . The lubricating engine oil of  claim 12  wherein the friction modifier mixture comprises an ethoxylated fatty acid ester and a glycerol fatty acid ester. 
     
     
         17 . The lubricating engine oil of  claim 12  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV and/or Group V base oil the friction modifier mixture comprises an ethoxylated fatty acid ester and a glycerol fatty acid ester. 
     
     
         18 . The lubricating engine oil of  claim 12  wherein the weight ratio of the first friction modifier to the other friction modifier is from 0.1:1 to 1:0.1. 
     
     
         19 . The lubricating engine oil of  claim 12  wherein the lubricating oil base stock is present in an amount of from 70 weight percent to 95 weight percent, and the friction modifier mixture is present in an amount of from 0.01 weight percent to 2.5 weight percent, based on the total weight of the formulated oil. 
     
     
         20 . The lubricating engine oil of  claim 12  wherein the lubricating oil base stock is present in an amount of from 70 weight percent to 95 weight percent, and the friction modifier mixture is present in an amount of from 0.01 weight percent to 1.0 weight percent, based on the total weight of the formulated oil. 
     
     
         21 . The lubricating engine oil of  claim 12  wherein the lubricating oil further comprises one or more of an anti-wear additive, viscosity index improver, antioxidant, detergent, dispersant, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, anti-rust additive, and organic metallic friction modifier. 
     
     
         22 . The lubricating engine oil of  claim 12  wherein the lubricating oil is a passenger vehicle engine oil (PVEO).