Lubricating oil composition for automobile transmission and lubricating method using same

Abstract

The present invention relates to an automatic transmission lubricating oil composition, and particularly to an automatic transmission lubricating oil composition comprising an oil of lubricating viscosity, an ashless dispersant, an anti-oxidant, a phosphorus-based anti-wear agent and a friction-modifier, wherein more than 310 ppm of phosphorus is contained, thereby being useful for lubricating or operating an automatic transmission comprising a transmission clutch using a slip lock-up torque converter and a paper based clutch material and a planetary gear system, especially six-speed automatic transmission.

1 . A lubricating oil composition for a six-speed transmission having a slipping torque converter clutch and Ravigneaux gear set, the composition comprising:
 100 weight parts of an oil of lubricating viscosity;   0.5-5 weight parts of an ashless dispersant;   0.05-5 weight parts of an anti-oxidant;   0.03-4.75 weight parts of a phosphorus-based anti-wear agent; and   0.05-5 weight parts of a friction modifier,   wherein phosphorus is contained at least 310 parts per million.   
   
   
       2 . The lubricating oil composition of  claim 1 , wherein the oil of lubricating viscosity is selected from the group consisting of a Group II oil, a Group III oil, a Group IV oil, a Group V oil and a mixture thereof. 
   
   
       3 . The lubricating oil composition of  claim 1 , wherein the ashless dispersant is selected from the group consisting of (a) a long-chain substituted hydrocarbil succinimide or hydrocarbil succinamide, (b) a mixed ester/amide of a long-chain hydrocarbil-substituted succinic acid, (c) a hydroxyester of a long-chain hydrocarbil-substituted succinic acid, and (d) a Mannich condensation product of a long-chain hydrocarbil-substituted phenol, formaldehyde and polyamine. 
   
   
       4 . The lubricating oil composition of  claim 1 , wherein the ashless dispersant is a long-chained alkenyl succinimide. 
   
   
       5 . The lubricating oil composition of  claim 1 , wherein the anti-oxidant is an aromatic amine or a hindered phenol. 
   
   
       6 . The lubricating oil composition of  claim 1 , wherein the phosphorus-based anti-wear agent is an organic phosphite or an amine salt of phosphorus acid. 
   
   
       7 . The lubricating oil composition of  claim 1 , wherein the phosphorus-based anti-wear agent is prepared by reacting phosphorus acid with a polyamine-based ashless dispersant. 
   
   
       8 . The lubricating oil composition of  claim 1 , wherein the friction modifier is selected from the group consisting of fatty acid amides, fatty epoxides, fatty amines, borated glycerol esters, alkoxylated fatty amines, borated alkoxylated amines, fatty imidazolines, condensation products of carboxylic acids and anhydrides with polyamines. 
   
   
       9 . The lubricating oil composition of  claim 1 , wherein the friction modifier is a reaction product of 3-octadecenyl succinic acid anhydride and a polyamine. 
   
   
       10 . The lubricating oil composition of  claim 1 , which has a kinematic viscosity at 100° C. of 5.2 cSt or higher and a −40° C. Brookfield viscosity of 12,000 cP or lower. 
   
   
       11 . A method for lubricating a six speed automatic transmission having a slipping torque converter clutch and Ravigneaux gear set comprising supplying to said transmission the lubricating oil composition of  claim 1 .