Lubricating oil composition

Abstract

There is provided a lubricating oil composition that has good friction performance and friction performance durability, and which is unlikely to cause degradation of oil seals made from fluororubbers, and which is particularly useful as an automatic transmission fluid. This lubricating oil composition is produced by adding a phosphorus/nitrogen-containing ashless dispersant of 0.2 to 8 wt % with a nitrogen/phosphorus ratio of 1.5 to 2.8, a friction modifier of 0.01 to 5 wt %, a metal-containing detergent of 0.005 to 2 wt %, and an antioxidant of 0.1 to 5 wt % as additives to a base oil with a lubricating viscosity.

1 . A lubricating oil composition, produced by adding a phosphorus/nitrogen-containing ashless dispersant of 0.2 to 8 wt % with a nitrogen/phosphorus ratio of 1.5 to 2.8, a friction modifier of 0.01 to 5 wt %, a metal-containing detergent of 0.005 to 2 wt %, and an antioxidant of 0.1 to 5 wt % as additives to a base oil with a lubricating viscosity, wherein the amounts in which the additives are added are in percentages with respect to the total weight of the lubricating oil composition. 
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the phosphorus/nitrogen-containing ashless dispersant is the product of a reaction between a nitrogen-containing ashless dispersant and phosphoric acid or phosphorous acid and wherein the ashless dispersant is non-borated. 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the phosphorus/nitrogen-containing ashless dispersant is the product of a reaction between polyisobutenylsuccinimide and phosphoric acid or phosphorous acid. 
     
     
         4 . The lubricating oil composition according to  claim 3 , wherein the polyisobutenylsuccinimide is a polyisobutenylsuccinimide with a bis structure. 
     
     
         5 . The lubricating oil composition according to  claim 1 , wherein the friction modifier is a C 6  to C 30  hydrocarbon substituted succinimide 
     
     
         6 . The lubricating oil composition according to  claim 5 , wherein the succinimide is the product of a reaction between ammonia and an alkenylsuccinic anhydride in which the alkenyl group is an internal olefin obtained by the isomerization of an olefinic double bond of a linear alpha olefin with 10 to 30 carbon atoms. 
     
     
         7 . The lubricating oil composition according to  claim 1 , wherein the friction modifier is a fatty acid amide. 
     
     
         8 . The lubricating oil composition according to  claim 7 , wherein the fatty acid amide is a reaction product obtained by a condensation reaction of an amine and a monovalent fatty acid with 6 to 30 carbon atoms. 
     
     
         9 . The lubricating oil composition according to  claim 5 , wherein the friction modifier includes succinimide and a fatty acid amide compound. 
     
     
         10 . The lubricating oil composition according to  claim 1 , wherein the metal-containing detergent is an alkali metal sulfonate. 
     
     
         11 . The lubricating oil composition according to  claim 1 , wherein the antioxidant is one or more ashless antioxidants selected from the group consisting of amine compounds having an antioxidant property, and phenol compounds having an antioxidant property. 
     
     
         12 . An automatic transmission lubricating oil composition comprising 0.2 to 8 wt % of a phosphorolyated polyisobutenyl succinimide having a nitrogen/phosphorus mass ratio of 1.5 to 2.8 wherein the polyisobutenyl group has an average molecular weight of 900 to 2300; 0.01 to 5 wt % a friction modifier succinimide derived from the reaction product of an isomerized C 6  to C 30  alkenyl succinic anhydride with an amine selected from the group of ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; a metal-containing detergent of 0.005 to 2 wt %; and an antioxidant of 0.1 to 5 wt % as additives to a base oil with a lubricating viscosity, wherein the amounts in which the additives are added are in percentages with respect to the total weight of the lubricating oil composition. 
     
     
         13 . The automatic transmission lubricating oil composition according to  claim 12 , wherein the phosphorolyated polyisobutenyl succinimide is non-borated. 
     
     
         14 . The automatic transmission lubricating oil composition according to  claim 12  wherein the total phosphorous content in the lubricating oil composition is less than 700 parts per million phosphorous. 
     
     
         15 . A method for improving fluororubber seal compatibility while maintaining stability of the coefficient of friction as measured according to the JASCO M315:2004 in an automatic transmission comprising using an automatic transmission lubricating oil composition comprising 0.2 to 8 wt % of a phosphorolyated polyisobutenyl succinimide having a nitrogen/phosphorus mass ratio of 1.5 to 2.8 wherein the polyisobutenyl group has an average molecular weight of 900 to 2300; 0.01 to 5 wt % a friction modifier succinimide derived from the reaction product of an isomerized C 6  to C 30  alkenyl succinic anhydride with an amine selected from the group of ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; a metal-containing detergent of 0.005 to 2 wt %; and an antioxidant of 0.1 to 5 wt % as additives to a base oil with a lubricating viscosity, wherein the amounts in which the additives are added are in percentages with respect to the total weight of the lubricating oil composition.