Lubricating oil compositions

Abstract

Soot induced kinematic viscosity increase of lubricating oil compositions for diesel engines equipped with EGR systems can be ameliorated by selection of viscosity modifier, lubricating oil flow improvers, detergents and/or dispersants.

1 . A lubricating oil composition having a sulfur content of less than 0.3 wt. %, said lubricating oil composition comprising a major amount of oil of lubricating viscosity, a minor amount of one or more high molecular weight polymers comprising (i) olefin copolymers containing alkyl or aryl amine, or amide groups, nitrogen-containing heterocyclic groups or ester linkages and/or (ii) acrylate or alkylacrylate copolymer derivatives having dispersing groups; and a minor amount of one or more neutral and/overbased metal-containing detergents, wherein from about 60% to 100% of the total amount of detergent surfactant is phenate and/or salicylate.  
     
     
         2 . The lubricating oil composition of  claim 1 , wherein said high molecular weight polymer comprises an olefin copolymer containing aryl amine groups.  
     
     
         3 . The lubricating oil composition of  claim 1 , wherein said one or more neutral and/overbased metal-containing detergents provide said lubricating oil composition with from about 6 to about 50 mmoles of phenate surfactant per kilogram of finished oil.  
     
     
         4 . The lubricating oil composition of  claim 1 , further comprising an amount of nitrogen-containing dispersant contributing no more than about 3.5 mmoles of basic nitrogen per 100 grams of said lubricating oil composition, wherein greater than 50 wt. % of the total amount of dispersant nitrogen is non-basic  
     
     
         5 . The lubricating oil composition of  claim 4 , wherein dispersant nitrogen is provided to said composition by dispersant, or a mixture of dispersants derived from hydrocarbon polymers having an average Mn of from about 1500 to about 3000, and said dispersant, or mixture of dispersants contributes to said lubricating oil composition from about 0.10 to about 0.18 wt. % of nitrogen, based on the total weight of the lubricating oil composition.  
     
     
         6 . The lubricating oil composition of  claim 4 , wherein at least one of said nitrogen-containing dispersant is derived from highly reactive polyisobutylene, having a terminal vinylidene content of at least 65%.  
     
     
         7 . The lubricating oil composition of  claim 6 , wherein said highly reactive polyisobutylene has an average M n  of from about 1500 to about 3000.  
     
     
         8 . The lubricating oil composition of  claim 7 , wherein said dispersant, or mixture of dispersants contributes to said lubricating oil composition from about 0.10 to about 0.18 wt. % of nitrogen, based on the total weight of the lubricating oil composition.  
     
     
         9 . The lubricating oil composition of  claim 4 , wherein at least a portion of the basic nitrogen of said nitrogen-containing dispersant is rendered non-basic by reacting said nitrogen-containing dispersant with a compound selected from alkyl acetoacetates; formic acid; glycolic acid; alkyl and alkylene carbonates; maleic anhydride and succinic anhydride.  
     
     
         10 . The lubricating oil composition of  claim 9 , wherein dispersant provides the lubricating oil composition with from about 1 to about 7 mmols of hydroxyl per 100 grams of finished oil.  
     
     
         11 . The lubricating oil composition of  claim 1 , wherein said detergent is selected from mixed surfactant phenate/salicylate detergents, sulfur-free phenate detergents, and mixtures thereof  
     
     
         12 . The lubricating oil composition of  claim 1 , wherein said oil of lubricating viscosity has a VI of at least 120.  
     
     
         13 . The lubricating oil composition of  claim 1 , wherein said oil of lubricating viscosity has a saturates content of at least 90.  
     
     
         14 . A lubricating oil composition of  claim 1 , having a 0 W or 5 W viscosity grade.  
     
     
         15 . A lubricating oil composition of  claim 1 , substantially free of sulfur-containing phenate detergent.  
     
     
         16 . A lubricating oil composition of  claim 1 , having a Noack volatility of less than 12 mass %.  
     
     
         17 . A lubricating oil composition of  claim 15 , having a Noack volatility of less than 10 mass %.  
     
     
         18 . A lubricating oil composition of  claim 1 , having a phosphorus content of less than 800 ppm.  
     
     
         19 . A lubricating oil composition of  claim 18 , having a phosphorus content of from about 300 ppm to about 800 ppm.  
     
     
         20 . The lubricating oil composition of  claim 1 , further comprising at least one an aminic antioxidant, phenolic antioxidant, or a combination thereof.  
     
     
         21 . A method of operating a compression ignited engine provided with an exhaust gas recirculation system which method comprises lubricating said engine with a lubricating oil composition of  claim 1 .  
     
     
         22 . The method of  claim 21 , wherein said compression ignited engine is fuelled by a diesel fuel containing less than 50 ppm of sulfur.  
     
     
         23 . The method of  claim 21 , wherein said engine is a heavy duty diesel engine and said exhaust gas recirculation system cools intake air and/or exhaust gas recirculation streams to below the dew point for at least 10% of the time said engine is in operation.  
     
     
         24 . A lubricating oil composition having a sulfur content of less than 0.3 wt. %, said lubricating oil composition comprising a major amount of oil of lubricating viscosity selected from Group I, Group II and Group III mineral oil, and mixtures thereof, a minor amount of one or more high molecular weight polymers comprising (i) copolymers of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly (conjugated diene), wherein the hydrogenated poly(monovinyl aromatic hydrocarbon) segment comprises at least about 20 wt. % of the copolymer; (ii) olefin copolymers containing alkyl or aryl amine, or amide groups, nitrogen-containing heterocyclic groups or ester linkages and/or (iii) acrylate or alkylacrylate copolymer derivatives having dispersing groups; a minor amount of a nitrogen-containing dispersant derived from highly reactive polyisobutylene, having a terminal vinylidene content of at least 65%.  
     
     
         25 . The lubricating oil composition of  claim 24 , wherein said high molecular weight polymer is an olefin copolymer containing aryl amine groups.  
     
     
         26 . The lubricating oil composition of  claim 24 , further comprising and a minor amount of one or more neutral and/overbased metal-containing detergents selected from mixed surfactant phenate/salicylate detergents, phenate detergents, salicylate detergents and mixtures thereof.  
     
     
         27 . The lubricating oil composition of  claim 26 , wherein from about 60% to 100% of the total amount of detergent surfactant is phenate and/or salicylate.  
     
     
         28 . The lubricating oil composition of  claim 26 , wherein said detergents are selected from the group consisting of mixed surfactant phenate/salicylate detergents, sulfur-phenate detergents, and mixtures thereof.  
     
     
         29 . The lubricating oil composition of  claim 24 , wherein said highly reactive polyisobutylene has an average M n  of from about 1500 to about 3000.  
     
     
         30 . The lubricating oil composition of  claim 29 , wherein said nitrogen-containing dispersant contribute from about 0.10 to about 0.18 wt. % of nitrogen, based on the total weight of the lubricating oil composition, and no more than about 3.5 mmoles of basic nitrogen per 100 grams of said lubricating oil composition, wherein greater than 50 wt. % of the total amount of dispersant nitrogen is non-basic.  
     
     
         31 . The lubricating oil composition of  claim 30 , wherein at least a portion of the basic nitrogen of said nitrogen-containing dispersant is rendered non-basic by reacting said nitrogen-containing dispersant with a compound selected from alkyl acetoacetates; formic acid; glycolic acid; alkyl and alkylene carbonates; maleic anhydride and succinic anhydride.  
     
     
         32 . The lubricating oil composition of  claim 24 , wherein said oil of lubricating viscosity has a VI of at least 120.  
     
     
         33 . The lubricating oil composition of  claim 24 , wherein said oil of lubricating viscosity has a saturates content of at least 90.  
     
     
         34 . A lubricating oil composition of  claim 24 , having a 0 W or 5 W viscosity grade.  
     
     
         35 . A lubricating oil composition of  claim 24 , having a Noack volatility of less than 12 mass %.  
     
     
         36 . A lubricating oil composition of  claim 24 , having a phosphorus content of less than 800 ppm.  
     
     
         37 . The lubricating oil composition of  claim 24 , further comprising at least one an aminic antioxidant, phenolic antioxidant, or a combination thereof.  
     
     
         38 . A method of operating a compression ignited engine provided with an exhaust gas recirculation system which method comprises lubricating said engine with a lubricating oil composition of  claim 24 .  
     
     
         39 . The method of  claim 25 , wherein said compression ignited engine is fuelled by a diesel fuel containing less than 50 ppm of sulfur.  
     
     
         40 . The method of  claim 38 , wherein said engine is a heavy duty diesel engine and said exhaust gas recirculation system cools intake air and/or exhaust gas recirculation streams to below the dew point for at least 10% of the time said engine is in operation.  
     
     
         41 . A lubricating oil composition comprising a major amount of oil of lubricating viscosity, a minor amount of one or more high molecular weight polymers comprising (i) copolymers of hydrogenated poly(monovinyl aromatic hydrocarbon) and poly (conjugated diene), wherein the hydrogenated poly(monovinyl aromatic hydrocarbon) segment comprises at least about 20 wt. % of the copolymer; (ii) olefin copolymers containing alkyl or aryl amine, or amide groups, nitrogen-containing heterocyclic groups or ester linkages and/or (iii) acrylate or alkylacrylate copolymer derivatives having dispersing groups; and a minor amount of one or more neutral and/overbased metal-containing detergents selected from the group consisting of mixed surfactant phenate/salicylate detergents, sulfur-free phenate detergents, and mixtures thereof.  
     
     
         42 . The lubricating oil composition of  claim 41 , wherein said high molecular weight polymer is an olefin copolymer containing aryl amine groups.  
     
     
         43 . The lubricating oil composition of  claim 41 , wherein from about 60% to 100% of the total amount of detergent surfactant is phenate and/or salicylate.  
     
     
         44 . A lubricating oil composition of  claim 41 , substantially free of sulfur-containing phenate detergent.  
     
     
         45 . The lubricating oil composition of  claim 41 , wherein said one or more neutral and/overbased metal-containing detergents provide said lubricating oil composition with from about 6 to about 50 mmoles of phenate surfactant per kilogram of finished oil.  
     
     
         46 . The lubricating oil composition of  claim 41 , further comprising an amount of nitrogen-containing dispersant contributing no more than about 3.5 mmoles of basic nitrogen per 100 grams of said lubricating oil composition, wherein greater than 50 wt. % of the total amount of dispersant nitrogen is non-basic  
     
     
         47 . The lubricating oil composition of  claim 46 , wherein dispersant nitrogen is provided to said composition by dispersant, or a mixture of dispersants derived from hydrocarbon polymers having an average M n  of from about 1500 to about 3000, and said dispersant, or mixture of dispersants contributes to said lubricating oil composition from about 0.10 to about 0.18 wt. % of nitrogen, based on the total weight of the lubricating oil composition.  
     
     
         48 . The lubricating oil composition of  claim 41 , further comprising at least one of said nitrogen-containing dispersant is derived from highly reactive polyisobutylene, having a terminal vinylidene content of at least 65%.  
     
     
         49 . The lubricating oil composition of  claim 48 , wherein said highly reactive polyisobutylene has an average Mn of from about 1500 to about 3000.  
     
     
         50 . The lubricating oil composition of  claim 49 , wherein said dispersant, or mixture of dispersants contributes to said lubricating oil composition from about 0.10 to about 0.18 wt. % of nitrogen, based on the total weight of the lubricating oil composition.  
     
     
         51 . The lubricating oil composition of  claim 49 , wherein at least a portion of the basic nitrogen of said nitrogen-containing dispersant is rendered non-basic by reacting said nitrogen-containing dispersant with a compound selected from alkyl acetoacetates; formic acid; glycolic acid; alkyl and alkylene carbonates; maleic anhydride and succinic anhydride.  
     
     
         52 . The lubricating oil composition of  claim 51 , wherein dispersant provides the lubricating oil composition with from about 1 to about 7 mmols of hydroxyl per 100 grams of finished oil.  
     
     
         53 . The lubricating oil composition of  claim 41 , wherein said lubricating oil composition has a sulfur content of less than 0.3 wt. %.  
     
     
         54 . The lubricating oil composition of  claim 41 , wherein said oil of lubricating viscosity has a VI of at least 120.  
     
     
         55 . The lubricating oil composition of  claim 41 , wherein said oil of lubricating viscosity has a saturates content of at least 90.  
     
     
         56 . A lubricating oil composition of  claim 41 , having a 0 W or 5 W viscosity grade.  
     
     
         57 . A lubricating oil composition of  claim 41 , substantially free of sulfur-containing phenate detergent.  
     
     
         58 . A lubricating oil composition of  claim 41 , having a Noack volatility of less than 12 mass %.  
     
     
         59 . A lubricating oil composition of  claim 58 , having a Noack volatility of less than 10 mass %.  
     
     
         60 . A lubricating oil composition of  claim 41 , having a phosphorus content of less than 800 ppm.  
     
     
         61 . A lubricating oil composition of  claim 60 , having a phosphorus content of from about 300 ppm to about 800 ppm.  
     
     
         62 . The lubricating oil composition of  claim 41 , further comprising at least one an aminic antioxidant, phenolic antioxidant, or a combination thereof.  
     
     
         63 . A method of operating a compression ignited engine provided with an exhaust gas recirculation system which method comprises lubricating said engine with a lubricating oil composition of  claim 41 .  
     
     
         64 . The method of  claim 63 , wherein said compression ignited engine is fuelled by a diesel fuel containing less than 50 ppm of sulfur.  
     
     
         65 . The method of  claim 63 , wherein said engine is a heavy duty diesel engine and said exhaust gas recirculation system cools intake air and/or exhaust gas recirculation streams to below the dew point for at least 10% of the time said engine is in operation.