Extended drain diesel lubricant formulations

Abstract

An additive concentrate, lubricant composition, and method of operating a diesel engine on the lubricant composition wherein the lubricant composition exhibits extended service life. The concentrate and lubricant composition include a sulfonate detergent and a phenate detergent, wherein the phenate detergent is present in an amount that is greater than 15 percent by weight of the total weight of detergents in the lubricant composition, and an antioxidant selected from hindered phenolic derivatives of C 3 to C 6 acids and C 7 to C 9 esters of hindered phenolic derivatives of C 3 to C 6 acids. The lubricant composition is substantially devoid of zinc dialkyldithiophosphate compounds.

1 . A lubricant composition for a diesel engine comprising:
 a major amount of oil of lubricating viscosity;   a sulfonate detergent and a phenate detergent, wherein the phenate detergent is present in an amount that is greater than 15 percent by weight of the total weight of detergents in the lubricant composition; and   a minor amount of an antioxidant additive selected from the group consisting essentially of hydroxy phenyl acids and hydroxy phenyl esters of the formula:   
       
         
           
           
               
               
           
         
         wherein each R 1  is a primary, secondary or tertiary alkyl group having from 3 to 6 carbon atoms and R 2  is selected from the group consisting essentially of C 3  to C 6  acids and C 7  to C 9  esters of the C 3  to C 6  acids, and wherein the lubricant composition is substantially devoid of zinc dialkyldithiophosphate compounds. 
       
     
     
         2 . The lubricant composition of  claim 1 , wherein the antioxidant additive comprises di-tertiary alkyl hydroxyphenylpropionic acid. 
     
     
         3 . The lubricant composition of  claim 1 , wherein the antioxidant additive comprises C 7  to C 9  ester of di-tertiary alkyl hydroxyphenylpropionic acid. 
     
     
         4 . The lubricant composition of  claim 1 , further comprising a triazole compound. 
     
     
         5 . The lubricant composition of  claim 4 , wherein the triazole compound is selected from the group consisting essentially of aminotriazole and hydrocarbyl substituted bis-aminotriazoles. 
     
     
         6 . The lubricant composition of  claim 5 , wherein the triazole compound comprises alkyl bis-1,2,4-triazole-3-amine. 
     
     
         7 . The lubricant composition of  claim 6 , wherein the alkyl group of the alkyl bis-1,2,4-triazole-3-amine comprises polyisobutylene having greater than about 50 weight percent terminal vinylidene content. 
     
     
         8 . An additive concentrate for a diesel engine lubricant composition comprising:
 a sulfonate detergent and a phenate detergent, wherein the phenate detergent is present in an amount that is greater than 15 percent by weight of the total weight of detergents in the additive concentrate; and   an antioxidant selected from the group consisting essentially of hydroxy phenyl acids and hydroxy phenyl esters of the formula:   
       
         
           
           
               
               
           
         
         wherein each R 1  is a primary, secondary or tertiary alkyl group having from 3 to 6 carbon atoms and R 2  is selected from the group consisting essentially of C 3  to C 6  acids and C 7  to C 9  esters of the C 3  to C 6  acids, and wherein a lubricant composition comprising the additive concentrate is substantially devoid of zinc dialkyldithiophosphate compounds. 
       
     
     
         9 . The additive concentrate of  claim 8 , wherein the antioxidant additive comprises di-tertiary alkyl hydroxyphenylpropionic acid. 
     
     
         10 . The additive concentrate of  claim 8 , wherein the antioxidant additive comprises C 7  to C 9  ester of di-tertiary alkyl hydroxyphenylpropionic acid. 
     
     
         11 . The additive concentrate of  claim 8 , further comprising a triazole compound. 
     
     
         12 . The additive concentrate of  claim 11 , wherein the triazole compound is selected from the group consisting essentially of aminotriazole and hydrocarbyl substituted bis-aminotriazoles. 
     
     
         13 . The additive concentrate of  claim 12 , wherein the triazole compound comprises alkyl bis-1,2,4-triazole-3-amine. 
     
     
         13 . The additive concentrate  claim 13 , wherein the alkyl group of the alkyl bis 1,2,4-triazole-3-amine comprises polyisobutylene having greater than about 50 weight percent terminal vinylidene content. 
     
     
         14 . A method for extending the drain interval for a lubricant for a medium speed diesel engine comprising:
 supplying as the lubricant, a lubricant composition comprising a sulfonate detergent and a phenate detergent, wherein the phenate detergent is present in an amount that is greater than 15 percent by weight of the total weight of detergents in the lubricant composition; and an antioxidant selected from the group consisting essentially of hindered phenolic derivatives of C 3  to C 6  acids and C 7  to C 9  esters of hindered phenolic derivatives of C 3  to C 6  acids, wherein the lubricant composition is substantially devoid of zinc dialkydithiophosphate compounds; and   operating the engine on the lubricant composition for an extended period of time between lubricant drain intervals.   
     
     
         15 . The method of  claim 14  wherein the antioxidant comprises a compound of the formula: 
       
         
           
           
               
               
           
         
         wherein each R 1  is a primary, secondary or tertiary alkyl group having from 3 to 6 carbon atoms and R 2  is selected from the group consisting essentially of C 3  to C 6  acids and C 7  to C 9  esters of the C 3  to C 6  acids. 
       
     
     
         16 . The method of  claim 14 , wherein the antioxidant comprises di-tertiary alkyl hydroxyphenylpropionic acid. 
     
     
         17 . The method of  claim 14 , wherein the antioxidant additive comprises C 7  to C 9  ester of di-tertiary alkyl hydroxyphenylpropionic acid. 
     
     
         18 . The method of  claim 14 , wherein the lubricant composition further comprises a triazole compound. 
     
     
         19 . The method of  claim 18 , wherein the triazole compound is selected from the group consisting essentially of aminotriazole and hydrocarbyl substituted bis-aminotriazoles. 
     
     
         20 . The method of  claim 19 , wherein the triazole compound comprises alkyl bis-1,2,4-triazole-3-amine. 
     
     
         21 . The method of  claim 20 , wherein the alkyl group of the alkyl bis 1,2,4-triazole-3-amine comprises polyisobutylene having greater than about 50 weight percent terminal vinylidene content. 
     
     
         22 . The method of  claim 14 , wherein the extended period of time is greater than about 200 days between drain intervals. 
     
     
         23 . The method of  claim 14 , wherein the extended period of time is greater than about 250 days between drain intervals. 
     
     
         24 . The method of  claim 14 , wherein the medium speed diesel engine is operated on a biodiesel fuel.