Multifunctional Driveline Fluid

Abstract

A composition including 1 to 20 weight percent of a compound having a traction coefficient of at least about 0.045, at least 50 weight percent of an oil of lubricating viscosity, a phosphorus compound and 2,5-dimercapto-1,3,4-thiadiazole or a derivative thereof, and having a kinematic viscosity at 100° C. of up to about 12 mm2/sec, is suitable for lubricating a transmission.

1 . A lubricant composition suitable for lubricating a transmission, said composition comprising:
 (a) about 1 to about 20 weight percent of a compound having a traction coefficient of at least about 0.045, selected from the group consisting of: (i) hydrocarbons containing non-aromatic cyclic structures, (ii) polybutenes of number average molecular weight about 180 to about 600, (iii) esters having a branched or non-aromatic cyclic alkyl moiety, and mixtures thereof;   (b) at least about 50 weight percent of an oil of lubricating viscosity, other than a material of component (a);   (c) a phosphorus acid or phosphorus ester or salt thereof; and   (d) 2,5-dimercapto-1,3,4-thiadiazole or a derivative thereof.   said lubricant composition having a kinematic viscosity at 100° C. of up to about 12 mm 2 /sec.   
   
   
       2 . The composition of  claim 1  wherein the compound having a traction coefficient of at least about 0.045 is a material having a traction coefficient of about 0.05 to about 0.12. 
   
   
       3 . The composition of  claim 1  wherein the ester molecule (a)(iii) comprises a polyol ester having a branched or non-aromatic cyclic alkyl moiety in the acid portion thereof, or in both the alcohol and acid portions. 
   
   
       4 . The composition of  claim 1  wherein the compound having a traction coefficient of at least about 0.045 comprises a pentaerythritol ester. 
   
   
       5 . The composition of  claim 1  wherein the amount of the compound having a traction coefficient of at least about 0.045 is about 5 to about 18 percent by weight 
   
   
       6 . The composition of  claim 1  wherein the oil of lubricating viscosity comprises a synthetic oil. 
   
   
       7 . The composition of  claim 1  wherein at least about 50 percent by weight of the oil of lubricating viscosity is a synthetic oil. 
   
   
       8 . The composition of  claim 6  wherein the synthetic oil is a poly-α-olefin. 
   
   
       9 . The composition of  claim 1  wherein the phosphorus acid or phosphorus ester or salt of a phosphorus ester is selected from the group consisting of phosphorus acids, dialkyl hydrogen phosphites, metal or amine dihydrocarbyldithiophosphate salts, metal or amine mono- and dihydrocarbylphosphate salts, and mixtures thereof. 
   
   
       10 . The composition of  claim 1  wherein the phosphorus acid or phosphorus ester or salt of a phosphorus ester is present in an amount to provide about 0.03 to about 0.1% by weight phosphorus to the composition. 
   
   
       11 . The composition of  claim 1  wherein the 2,5-dimercapto-1,3,4-thiadiazole or derivative thereof is present in an amount of about 0.05 to about 4 percent by weight. 
   
   
       12 . The composition of  claim 1  wherein the 2,5-dimercapto-1,3,4-thiadiazole or derivative thereof is present in an amount to provide about 0.005 to about 1% by weight sulfur to the composition. 
   
   
       13 . The composition of  claim 1  further comprising a viscosity index modifier. 
   
   
       14 . A composition prepared by admixing the components of  claim 1 . 
   
   
       15 . A method for lubricating a transmission, comprising supplying thereto the composition of  claim 1 .