Lubricating oil compositions

Abstract

A lubricating oil composition comprising (a) a major amount of an oil of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent, (d) an antioxidant, and (e) an anti-wear agent, wherein the lubricating oil composition is free of any zinc dialkyl dithiophosphate compound and is substantially free of any phosphorus content is disclosed.

1 . A lubricating oil composition comprising (a) a major amount of an oil of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent, (d) an antioxidant, and (e) an anti-wear agent, wherein the lubricating oil composition is free of any zinc dialkyl dithiophosphate compound and is substantially free of any phosphorus content. 
   
   
       2 . The lubricating oil composition of  claim 1 , wherein the ashless dispersant is a bissuccinimide. 
   
   
       3 . The lubricating oil composition of  claim 2 , wherein the bissuccinimide ashless dispersant is derived from one or more polyalkylene succinic anhydrides. 
   
   
       4 . The lubricating oil composition of  claim 3 , wherein the polyalkylene group is a polyisobutenyl group having an average molecular weight of from about 900 to about 2300. 
   
   
       5 . The lubricating oil composition of  claim 3 , wherein the bissuccinimide is post-treated with ethylene carbonate. 
   
   
       6 . The lubricating oil composition of  claim 1 , wherein the amount of the ashless dispersant is about 3 wt. % to about 10 wt. %, based on the total weight of the lubricating oil composition. 
   
   
       7 . The lubricating oil composition of  claim 1 , wherein the at least one metal-containing detergent is an overbased alkaline earth metal sulfonate detergent having a total base number (TBN) of about 10 to about 450. 
   
   
       8 . The lubricating oil composition of  claim 1 , wherein the at least one metal-containing detergent comprises two metal-containing detergents. 
   
   
       9 . The lubricating oil composition of  claim 8 , wherein the two metal-containing detergents comprise a first metal-containing detergent which is an overbased alkaline earth metal sulfonate detergent having a TBN of about 150 to about 450 and a second metal-containing detergent which is an overbased alkaline earth metal sulfonate detergent having a TBN of about 10 to about 50. 
   
   
       10 . The lubricating oil composition of  claim 1 , wherein the amount of the at least one metal-containing detergent is about 0.5 wt. % to about 2 wt. %, based on the total weight of the lubricating oil composition. 
   
   
       11 . The lubricating oil composition of  claim 1 , wherein the antioxidant is a diphenylamine compound. 
   
   
       12 . The lubricating oil composition of  claim 11 , wherein the diphenylamine compound is selected from the group consisting of an alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated-α-naphthylamine. 
   
   
       13 . The lubricating oil composition of  claim 1 , wherein the antioxidant is selected from the group consisting of butyldiphenylamine, di-butyldiphenylamine, octyldiphenylamine, di-octyldiphenylamine, nonyldiphenylamine, di-nonyldiphenylamine, t-butyl-t-octyldiphenylamine and mixtures thereof. 
   
   
       14 . The lubricating oil composition of  claim 1 , wherein the amount of the antioxidant is about 0.2 wt. % to about 1 wt. %, based on the total weight of the lubricating oil composition. 
   
   
       15 . The lubricating oil composition of  claim 1 , wherein the anti-wear agent comprises a molybdenum-containing complex. 
   
   
       16 . The lubricating oil composition of  claim 16 , wherein the molybdenum-containing complex comprises a molybdenum/nitrogen complex. 
   
   
       17 . The lubricating oil composition of  claim 17 , wherein the molybdenum/nitrogen complex contains a basic nitrogen-containing compound having at least one basic nitrogen. 
   
   
       18 . The lubricating oil composition of  claim 17 , wherein the basic nitrogen-containing compound is selected from the group consisting of succinimides, carboxylic acid amides, hydrocarbyl monoamines, hydrocarbon polyamines, Mannich bases and mixtures thereof. 
   
   
       19 . The lubricating oil composition of  claim 1 , wherein the amount of the anti-wear agent is about 0.1 wt. % to about 2 wt. %, based on the total weight of the lubricating oil composition. 
   
   
       20 . The lubricating oil composition of  claim 1 , which is free of any phosphorus content. 
   
   
       21 . The lubricating oil composition of  claim 1 , further comprising at least one additive selected from the group consisting of a friction modifier, extreme pressure agent, viscosity index improver, pour point depressant and mixtures thereof. 
   
   
       22 . The lubricating oil composition of  claim 1 , wherein the lubricating oil composition has a wear reducing property greater than that of a corresponding lubricating oil composition in which a zinc dialkyl dithiophosphate compound is present therein. 
   
   
       23 . The lubricating oil composition of  claim 1 , which possesses a wear reducing property of at least about 20% greater than that of a corresponding lubricating oil composition in which a zinc dihydrocarbyl dithiophosphate compound is present therein. 
   
   
       24 . The lubricating oil composition of  claim 1 , which possesses a wear reducing property of at least about 25% greater than that of a corresponding lubricating oil composition in which a zinc dihydrocarbyl dithiophosphate compound is present therein. 
   
   
       25 . A method for reducing wear in an internal combustion engine, the method comprising operating the engine with a lubricating oil composition comprising (a) a major amount of an oil of lubricating viscosity, (b) an ashless dispersant, (c) at least one metal-containing detergent, (d) an antioxidant, and (e) an anti-wear agent, wherein the lubricating oil composition is free of any zinc dialkyl dithiophosphate compound and is substantially free of any phosphorus content. 
   
   
       26 . The method of  claim 25 , wherein the ashless dispersant is a bissuccinimide. 
   
   
       27 . The method of  claim 26 , wherein the bissuccinimide ashless dispersant is derived from one or more polyalkylene succinic anhydrides. 
   
   
       28 . The method of  claim 27 , wherein the polyalkylene group is a polyisobutenyl group having an average molecular weight of from about 900 to about 2300. 
   
   
       29 . The method of  claim 27 , wherein the bissuccinimide is post-treated with ethylene carbonate. 
   
   
       30 . The method of  claim 25 , wherein the amount of the ashless dispersant is about 3 wt. % to about 10 wt. %, based on the total weight of the lubricating oil composition. 
   
   
       31 . The method of  claim 25 , wherein the at least one metal-containing detergent is an overbased alkaline earth metal sulfonate detergent having a TBN of about 10 to about 450. 
   
   
       32 . The method of  claim 25 , wherein the at least one metal-containing detergent comprises two metal-containing detergents. 
   
   
       33 . The method of  claim 32 , wherein the two metal-containing detergents comprise a first metal-containing detergent which is an overbased alkaline earth metal sulfonate detergent having a TBN of about 150 to about 450 and a second metal-containing detergent which is an overbased alkaline earth metal sulfonate detergent having a TBN of about 10 to about 50. 
   
   
       34 . The method of  claim 25 , wherein the amount of the at least one metal-containing detergent is about 0.5 wt. % to about 2 wt. %, based on the total weight of the lubricating oil composition. 
   
   
       35 . The method of  claim 25 , wherein the antioxidant is a diphenylamine compound. 
   
   
       36 . The method of  claim 35 , wherein the diphenylamine compound is an alkylated diphenylamine. 
   
   
       37 . The method of  claim 25 , wherein the amount of the antioxidant is about 0.2 wt. % to about 1 wt. %, based on the total weight of the lubricating oil composition. 
   
   
       38 . The method of  claim 25 , wherein the anti-wear agent comprises a molybdenum-containing complex. 
   
   
       39 . The method of  claim 38 , wherein the molybdenum-containing complex comprises a molybdenum/nitrogen complex. 
   
   
       40 . The method of  claim 25 , wherein the anti-wear agent comprises a molybdenum succinimide complex. 
   
   
       41 . The method of  claim 25 , wherein the amount of the anti-wear agent is about 0.1 wt. % to about 2 wt. %, based on the total weight of the lubricating oil composition. 
   
   
       42 . The method of  claim 25 , which is free of any phosphorus content. 
   
   
       43 . The method of  claim 25 , further comprising at least one additive selected from the group consisting of a friction modifier, extreme pressure agent, viscosity index improver, pour point depressant and mixtures thereof. 
   
   
       44 . The method of  claim 25 , wherein the lubricating oil composition has a wear reducing property greater than that of a corresponding lubricating oil composition in which a zinc dialkyl dithiophosphate compound is present therein. 
   
   
       45 . An internal combustion engine lubricated with the lubricating oil composition of  claim 1 . 
   
   
       46 . An internal combustion engine lubricated with the lubricating oil composition of  claim 24 .