Method for improving engine fuel efficiency

Abstract

A method for improving fuel efficiency and friction reduction 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 tungsten organic complex as a minor component. 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 tungsten organic complex. A lubricating engine oil having a composition comprising a lubricating oil base stock as a major component, and a tungsten organic complex 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 for improving fuel efficiency and friction reduction 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 metal-containing organic complex friction modifier, as a minor component; wherein the metal-containing organic complex friction modifier comprises a tungsten organic complex that provides between 20 parts per million (ppm) and 500 ppm of tungsten to the formulated oil; 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 tungsten organic complex. 
     
     
         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 the tungsten organic complex is selected from the group consisting of: a tungsten dithiophosphate represented by the formula 
       
         
           
           
               
               
           
         
         wherein M is tungsten, R 1  and R 2  are the same or different, each of R 1  and R 2  contains from 1 to 30 carbon atoms and are an alkyl group, a cycloalkyl group, an aryl group or an alkylaryl group, and x and y are positive real numbers satisfying the equation x+y=4; and a tungsten dithiocarbamate represented by the formula 
       
       
         
           
           
               
               
           
         
         wherein M is tungsten, R 3  and R 4  are the same or different, each of R 3  and R 4  contains from 1 to 30 carbon atoms and are an alkyl group, a cycloalkyl group, an aryl group or an alkylaryl group, and m and n are positive real numbers satisfying the equation: m=n=4. 
       
     
     
         4 . The method of  claim 1  wherein the formulated oil further comprises at least one organic friction modifier, wherein said organic friction modifier is 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. 
     
     
         5 . The method of  claim 4  wherein the formulated oil further comprises an organic friction modifier mixture comprising a first organic friction modifier, and at least one other organic friction modifier different from said first organic friction modifier; wherein said first organic friction modifier and said at least one other organic 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. 
     
     
         6 . 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 glycerol mono-oleate and glycerol mono-stearate; the borated glycerol fatty acid ester is selected from borated glycerol mono-oleate and borated glycerol mono-sterate; and the fatty alcohol ether is selected from stearyl ether and myristyl ether. 
     
     
         7 . The method of  claim 4  wherein the at least one organic friction modifier comprises an ethoxylated fatty acid ester, a stearyl ether, or a mixture thereof. 
     
     
         8 . The method of  claim 1  wherein the oil base stock is present in an amount of from 70 weight percent to 95 weight percent, and the tungsten organic complex 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, 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 tungsten organic complex; 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 tungsten organic complex. 
     
     
         10 . A lubricating engine oil having a composition comprising a lubricating oil base stock as a major component; and a metal-containing organic complex friction modifier, as a minor component; wherein the metal-containing organic complex friction modifier comprises a tungsten organic complex that provides between 20 parts per million (ppm) and 500 ppm of tungsten to the formulated oil; 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 tungsten organic complex. 
     
     
         11 . The lubricating engine oil of  claim 10  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         12 . The lubricating engine oil of  claim 10  wherein the tungsten organic complex is selected from the group consisting of: a tungsten dithiophosphate represented by the formula 
       
         
           
           
               
               
           
         
         wherein M is tungsten, R 1  and R 2  are the same or different, each of R 1  and R 2  contains from 1 to 30 carbon atoms and are an alkyl group, a cycloalkyl group, an aryl group or an alkylaryl group, and x and y are positive real numbers satisfying the equation x+y=4; and a tungsten dithiocarbamate represented by the formula 
       
       
         
           
           
               
               
           
         
         wherein M is tungsten, R 3  and R 4  are the same or different, each of R 3  and R 4  contains from 1 to 30 carbon atoms and are an alkyl group, a cycloalkyl group, an aryl group or an alkylaryl group, and m and n are positive real numbers satisfying the equation: m+n=4. 
       
     
     
         13 . The lubricating engine oil of  claim 10  further comprising at least one organic friction modifier, wherein said organic friction modifier is 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. 
     
     
         14 . The lubricating engine oil of  claim 13  further comprising an organic friction modifier mixture comprising a first organic friction modifier, and at least one other organic friction modifier different from said first organic friction modifier; wherein said first organic friction modifier and said at least one other organic 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. 
     
     
         15 . The lubricating engine oil of  claim 13  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 glycerol mono-oleate and glycerol mono-stearate; the borated glycerol fatty acid ester is selected from borated glycerol mono-oleate 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 13  wherein the at least one organic friction modifier comprises an ethoxylated fatty acid ester, a stearyl ether, or a mixture thereof. 
     
     
         17 . The lubricating engine oil of  claim 10  wherein the oil base stock is present in an amount of from 70 weight percent to 95 weight percent, and the tungsten organic complex 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. 
     
     
         18 . The lubricating engine oil of  claim 10  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 tungsten organic complex; and wherein, in deposit measurements of the lubricating oil by thermo-oxidation engine oil simulation (TEOST 33C) measured by ASTM D6335, 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 tungsten organic complex. 
     
     
         19 . The lubricating engine oil of  claim 10  further comprising 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, and anti-rust additive. 
     
     
         20 . The lubricating engine oil of  claim 10  wherein the lubricating oil is a passenger vehicle engine oil (PVEO).