Method for improving engine fuel efficiency

Abstract

A method for improving friction reduction and fuel efficiency, while maintaining or improving wear protection, in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition comprising a lubricating oil base stock as a major component; and a detergent mixture comprising a first detergent having a TBN of less than about 100, and at least one other detergent different from said first detergent, as a minor component. The composition contains greater than about 4 weight percent of the first detergent, based on the total weight of the formulated oil. Friction reduction and fuel efficiency are improved and wear protection is maintained or improved as compared to friction reduction, fuel efficiency and wear protection achieved using a lubricating engine oil containing a detergent mixture having other than the first detergent having a TBN of less than about 100.

What is claimed is: 
     
         1 . A method for improving friction reduction and fuel efficiency, while maintaining or improving wear protection, 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 detergent mixture comprising a first detergent having a TBN of less than about 100, and at least one other detergent different from said first detergent, as a minor component; wherein said composition contains greater than about 4 weight percent of the first detergent, based on the total weight of the formulated oil; and wherein friction reduction and fuel efficiency are improved and wear protection is maintained or improved as compared to friction reduction, fuel efficiency and wear protection achieved using a lubricating engine oil containing a detergent mixture having other than the first detergent having a TBN of less than about 100. 
     
     
         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 lubricating oil base stock comprises a poly alpha olefin (PAO), or gas-to-liquid (GTL) oil base stock, in combination with a Group V base oil. 
     
     
         4 . The method of  claim 1  wherein the detergent mixture comprises said first detergent having a TBN of less than about 100 and at least one second detergent, different from said first detergent, having a TBN of less than about 100; said first detergent having a TBN of less than about 100 and at least one second detergent having a TBN between about 100 and about 200; said first detergent having a TBN of less than about 100 and at least one second detergent having a TBN greater than about 200; said first detergent having a TBN of less than about 100, at least one second detergent having a TBN between about 100 and about 200, and at least one third detergent having a ‘TBN greater than about 200. 
     
     
         5 . The method of  claim 4  wherein the first detergent, second detergent and third detergent are selected from metallic salicylates, sulfates, phenates, carboxylates, phosphates and sulfonates, and wherein the metallic salicylates, sulfates, phenates, carboxylates, phosphates and sulfonates are selected from alkali metals and alkaline earth metals. 
     
     
         6 . The method of  claim 4  wherein the first detergent, second detergent and third detergent are selected from metallic salicylates, sulfates, phenates, carboxylates, phosphates and sulfonates, and wherein the metallic salicylates, sulfates, phenates, carboxylates, phosphates and sulfonates are selected from calcium and magnesium. 
     
     
         7 . The method of  claim 1  wherein first detergent is calcium salicylate or calcium sulfonate. 
     
     
         8 . The method of  claim 1  wherein the oil base stock is present in an amount of from about 70 weight percent to about 95 weight percent, and the detergent mixture is present in an amount greater than about 4.0 weight percent to about 8.0 weight percent, based on the total weight of the formulated oil. 
     
     
         9 . The method of  claim 1  wherein the formulated 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, and anti-rust additive. 
     
     
         10 . 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 detergent mixture having other than the first detergent having a TBN of less than about 100. 
     
     
         11 . A lubricating engine oil having a composition comprising a lubricating oil base stock as a major component; and a detergent mixture comprising a first detergent having a TBN of less than about 100, and at least one other detergent different from said first detergent, as a minor component; wherein said composition contains greater than about 4 weight percent of the first detergent, based on the total weight of the formulated oil; and wherein said composition is sufficient for the lubricating engine oil to exhibit improved friction reduction and fuel efficiency and improved or maintained wear protection as compared to friction reduction, fuel efficiency and wear protection achieved using a lubricating engine oil containing a detergent mixture having other than the first detergent having TBN of less than about 100. 
     
     
         12 . The lubricating engine oil of  claim 11  wherein the lubricating oil base stock comprises a Group I, Group II, Group III, Group IV or Group V base oil. 
     
     
         13 . The lubricating engine oil of  claim 11  wherein the lubricating oil base stock comprises a poly alpha olefin (PAO), or gas-to-liquid (GTL) oil base stock, in combination with a Group V base oil. 
     
     
         14 . The lubricating engine oil of claim wherein the detergent mixture comprises said first detergent having a TBN of less than about 100 and at least one second detergent, different from said first detergent, having TBN of less than about 100; said first detergent having a TBN of less than about 100 and at least one second detergent having a TBN between about 100 and about 200; said first detergent having a TBN of less than about 100 and at least one second detergent having TBN greater than about 200; said first detergent having a TBN of less than about 100, at least one second detergent having a TBN between about 100 and about 200, and at least one third detergent having a TBN greater than about 200. 
     
     
         15 . The lubricating engine oil of  claim 14  wherein the first detergent, second detergent and third detergent are selected from metallic salicylates, sulfates, phenates, carboxylates, phosphates and sulfonates, and wherein the metallic salicylates, sulfates, phenates, carboxylates, phosphates and sulfonates are selected from alkali metals and alkaline earth metals. 
     
     
         16 . The lubricating engine oil of  claim 14  wherein the first detergent, second detergent and third detergent are selected from metallic salicylates, sulfates, phenates, carboxylates, phosphates and sulfonates, and wherein the metallic salicylates, sulfates, phenates, carboxylates, phosphates and sulfonates are selected from calcium and magnesium. 
     
     
         17 . The lubricating engine oil of  claim 11  wherein first detergent is calcium salicylate or calcium sulfonate. 
     
     
         18 . The lubricating engine oil of  claim 11  wherein the oil base stock is present in an amount of from about 70 weight percent to about 95 weight percent, and the detergent mixture is present in an amount greater than about 4.0 weight percent to about 8.0 weight percent, based on the total weight of the formulated oil. 
     
     
         19 . The lubricating engine oil of  claim 11  wherein the formulated 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, and anti-rust additive. 
     
     
         20 . The lubricating engine oil of  claim 11  comprising a passenger vehicle engine oil (PVEO).