Lubricating engine oil for improved wear protection and fuel efficiency

Abstract

Provided are lubricating engine oils including a lubricating oil base stock as a major component having a base oil viscosity at 100 deg. C. ranging from 4.5 to 7.5 cSt, and a carboxylic functionalized polymer dispersant with aromatic amine functionality, as a minor component, wherein the lubricating engine oils have a cold crank simulator viscosity at −30 deg. C. of less than 8500 mPa·s. The lubricating engine oils may provide improved engine wear protection at equivalent fuel efficiency or improved fuel efficiency at equivalent engine wear protection compared to a lubricating engine oil containing a dispersant as a minor component other than the carboxylic functionalized polymer with aromatic amine functionality. Methods of making the lubricating engine oil are also provided. The lubricating engine oils are useful in internal combustion engines including direct injection, gasoline and diesel engines.

1 . A multi-grade lubricating engine oil comprising a lubricating oil base stock as a major component, and a carboxylic functionalized polymer dispersant with aromatic amine functionality, as a minor component, wherein the lubricating engine oil base oil viscosity at 100 deg. C. ranges from 4.5 to 7.5 cSt, wherein the lubricating engine oil has a cold crank simulator viscosity at −30 deg. C. of less than 8500 mPa·s and wherein fuel efficiency as measured by HTHS (ASTM D4683) and/or engine wear protection as measured by HFRR wear scar (ISO Provisional Standard, TC22/SC7N959, 1995) are improved or maintained as compared to fuel efficiency and engine wear protection achieved using a multi-grade lubricating engine oil containing a dispersant as a minor component other than the carboxylic functionalized polymer with aromatic amine functionality. 
     
     
         2 . The oil of  claim 1 , wherein the lubricating oil base stock is selected from the group consisting of a Group I base stock, a Group II base stock, a Group III base stock, a Group IV base stock, Group V base stock and combinations thereof. 
     
     
         3 . The oil of  claim 1 , wherein the major component ranges from 50 to 99 wt. % and the minor component ranges from 1 to 15 wt. %, based on the total weight of the oil. 
     
     
         4 . The oil of  claim 1 , wherein the carboxylic functionalized polymer dispersant includes a polymer backbone comprising grafted ethylene-propylene (EP) copolymer, or grafted terpolymers of ethylene, propylene and non-conjugated diene, or a combination thereof. 
     
     
         5 . The oil of  claim 1 , wherein the aromatic amine functionality includes an amine group having at least 3 aromatic groups. 
     
     
         6 . The oil of  claim 5 , wherein the amine group having at least 3 aromatic groups is selected from the group consisting of bis[p-(p-aminoanilino)phenyl]-methane, 2-(7-amino-acridin-2-ylmethyl)-N-4-{4-[4-(4-amino-phenylamino)-benzyl]-phenyl}-benzene-1,4-diamine, N 4 -{4-[4-(4-amino-phenylamino)-benzyl]-phenyl}-2-[4-(4-amino-phenylamino)-cyclohexa-1,5-dienylmethyl]-benzene-1,4-diamine, N-[4-(7-amino-acridin-2-ylmethyl)-phenyl]-benzene-1,4-diamine, and combinations thereof. 
     
     
         7 . The oil of  claim 1 , further including a non-low viscosity dispersant at from 0.1 to 10 wt. %, based on the total weight of the oil. 
     
     
         8 . The oil of  claim 7 , wherein the non-low viscosity dispersant is selected from the group consisting of succinimides, succinate esters, succinate ester amides, alkylphenol-polyamine-coupled Mannich adducts and combinations thereof. 
     
     
         9 . The oil of  claim 1 , further comprising one or more of an anti-wear additive, viscosity index improver, antioxidant, detergent, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive. 
     
     
         10 . The oil of  claim 1 , wherein the lubricating engine oil is a heavy duty diesel engine oil (HDEO). 
     
     
         11 . The oil of  claim 1 , wherein the lubricating engine oil has a HTHS viscosity of less than 3.5 cSt. 
     
     
         12 . The oil of  claim 1 , wherein the lubricating engine oil has a HFRR average wear scar of less than or equal to 202 μm. 
     
     
         13 . A method for improving engine wear protection while maintaining or improving fuel efficiency, 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 carboxylic functionalized polymer dispersant with aromatic amine functionality, as a minor component, wherein the lubricating oil base oil viscosity at 100 deg. C. ranges from 4.5 to 7.5 cSt, wherein the lubricating oil has a cold crank simulator viscosity at −30 deg. C. of less than 8500 mPa·s and wherein the engine wear protection is improved by at least 10% as compared to the engine wear protection achieved using a formulated oil containing a dispersant as a minor component other than the carboxylic functionalized polymer with aromatic amine functionality. 
     
     
         14 . The method of  claim 13 , wherein the lubricating oil base stock is selected from the group consisting of a Group I base stock, a Group II base stock, a Group III base stock, a Group IV base stock, Group V base stock and combinations thereof. 
     
     
         15 . The method of  claim 13 , wherein the major component ranges from 50 to 99 wt. % and the minor component ranges from 1 to 15 wt. %, based on the total weight of the oil. 
     
     
         16 . The method of  claim 13 , wherein the carboxylic functionalized polymer dispersant includes a polymer backbone comprising grafted ethylene-propylene (EP) copolymer, or grafted terpolymers of ethylene, propylene and non-conjugated diene, or a combination thereof. 
     
     
         17 . The method of  claim 13 , wherein the aromatic amine functionality includes an amine group having at least 3 aromatic groups. 
     
     
         18 . The method of  claim 17 , wherein the amine group having at least 3 aromatic groups is selected from the group consisting of bis[p-(p-aminoanilino)phenyl]-methane, 2-(7-amino-acridin-2-ylmethyl)-N-4-{4-[4-(4-amino-phenylamino)-benzyl]-phenyl}-benzene-1,4-diamine, N 4 -{4-[4-(4-amino-phenylamino)-benzyl]-phenyl}-2-[4-(4-amino-phenylamino)-cyclohexa-1,5-dienylmethyl]-benzene-1,4-diamine, N-[4-(7-amino-acridin-2-ylmethyl)-phenyl]-benzene-1,4-diamine, and combinations thereof. 
     
     
         19 . The method of  claim 13 , further including a non-low viscosity dispersant at from 0.1 to 10 wt. %, based on the total weight of the oil. 
     
     
         20 . The method of  claim 19 , wherein the non-low viscosity dispersant is selected from the group consisting of succinimides, succinate esters, succinate ester amides, alkylphenol-polyamine-coupled Mannich adducts and combinations thereof. 
     
     
         21 . The method of  claim 13 , further comprising one or more of an anti-wear additive, viscosity index improver, antioxidant, detergent, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive. 
     
     
         22 . The method of  claim 13 , wherein the lubricating oil has a high shear viscosity at least 10% greater than a formulated oil containing a dispersant as a minor component other than the carboxylic functionalized polymer with aromatic amine functionality. 
     
     
         23 . The method of  claim 13 , wherein the lubricating oil has a HTHS viscosity of less than 3.5 cSt. 
     
     
         24 . The method of  claim 13 , wherein the lubricating engine oil has a HFRR average wear scar of less than or equal to 202 μm. 
     
     
         25 . A method for improving 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 carboxylic functionalized polymer dispersant with aromatic amine functionality, as a minor component, wherein the lubricating oil base oil viscosity at 100 deg. C. ranges from 4.5 to 7.5 cSt, wherein the lubricating oil has a cold crank simulator viscosity at −30 deg. C. of less than 8500 mPa·s, and wherein the fuel efficiency is improved by at least 10% as compared to the fuel efficiency achieved using a formulated oil containing a dispersant as a minor component other than the carboxylic functionalized polymer with aromatic amine functionality. 
     
     
         26 . The method of  claim 25 , wherein the lubricating oil base stock is selected from the group consisting of a Group I base stock, a Group II base stock, a Group III base stock, a Group IV base stock, Group V base stock and combinations thereof. 
     
     
         27 . The method of  claim 25 , wherein the major component ranges from 50 to 99 wt. % and the minor component ranges from 1 to 15 wt. %, based on the total weight of the oil. 
     
     
         28 . The method of  claim 25 , wherein the carboxylic functionalized polymer dispersant includes a polymer backbone comprising grafted ethylene-propylene (EP) copolymer, or grafted terpolymers of ethylene, propylene and non-conjugated diene, or a combination thereof. 
     
     
         29 . The method of  claim 25 , wherein the aromatic amine functionality includes an amine group having at least 3 aromatic groups. 
     
     
         30 . The method of  claim 29 , wherein the amine group having at least 3 aromatic groups is selected from the group consisting of bis[p-(p-aminoanilino)phenyl]-methane, 2-(7-amino-acridin-2-ylmethyl)-N-4-{4-[4-(4-amino-phenylamino)-benzyl]-phenyl}-benzene-1,4-diamine, N 4 -{4-[4-(4-amino-phenylamino)-benzyl]-phenyl}-2-[4-(4-amino-phenylamino)-cyclohexa-1,5-dienylmethyl]-benzene-1,4-diamine, N-[4-(7-amino-acridin-2-ylmethyl)-phenyl]-benzene-1,4-diamine, and combinations thereof. 
     
     
         31 . The method of  claim 25 , further including a non-low viscosity dispersant at from 0.1 to 10 wt. %, based on the total weight of the oil. 
     
     
         32 . The method of  claim 31 , wherein the non-low viscosity dispersant is selected from the group consisting of succinimides, succinate esters, succinate ester amides, alkylphenol-polyamine-coupled Mannich adducts and combinations thereof. 
     
     
         33 . The method of  claim 25 , further comprising one or more of an anti-wear additive, viscosity index improver, antioxidant, detergent, pour point depressant, corrosion inhibitor, metal deactivator, seal compatibility additive, anti-foam agent, inhibitor, and anti-rust additive. 
     
     
         34 . The method of  claim 25 , wherein the lubricating oil has a HTHS viscosity (ASTM D4683) at least 10% lower than a formulated oil containing a dispersant as a minor component other than the carboxylic functionalized polymer with aromatic amine functionality. 
     
     
         35 . The method of  claim 25 , wherein the engine is an internal combustion engine selected from the group consisting of a direct injection engine, a gasoline engine, and a diesel engine. 
     
     
         36 . The method of  claim 25 , wherein the lubricating oil has a HTHS viscosity of less than 3.5 cSt. 
     
     
         37 . The method of  claim 25 , wherein the lubricating engine oil has a HFRR average wear scar of less than or equal to 202 μm. 
     
     
         38 . A method of making a lubricating engine oil comprising:
 providing a lubricating oil base stock having a base oil viscosity at 100 deg. C. ranging from 4.5 to 7.5 cSt, and a carboxylic functionalized polymer dispersant with aromatic amine functionality, and   blending from 50 to 99 wt. %, based on the total weight of the oil, of the lubricating oil base stock with from 1 to 15 wt. %, based on the total weight of the oil, of the carboxylic functionalized polymer dispersant with aromatic amine functionality to form the lubricating engine oil,   wherein the lubricating engine oil has a cold crank simulator viscosity at −30 deg. C. of less than 8500 mPa·s.