Lubricant composition comprising a 2,5-dimercapto-1,3,4-thiadiazole alkyl polycarboxylate compound

Abstract

A lubricating oil additive composition comprising at least one organomolybdenum compound and at least one 2,5-dimercapto-1,3,4-thiadiazole alkyl polycarboxylate compound.

1 . A lubricating oil additive composition comprising:
 at least one organomolybdenum compound, and   at least one 2,5-dimercapto-1,3,4-thiadiazole alkyl (poly)carboxylate compound.   
     
     
         2 . The additive composition according to  claim 1 , wherein the organomolybdenum compound is chosen from dinuclear organomolybdenum compounds. 
     
     
         3 . The additive composition according to  claim 1 , wherein the 2,5-dimercapto-1,3,4-thiadiazole alkyl (poly)carboxylate compound is selected from compounds of the following formula (IV): 
       
         
           
           
               
               
           
         
         wherein R′ is a C 1 -C 34  alkyl moiety substituted with at least one C 1 -C 34  alkyl carboxylate moiety. 
       
     
     
         4 . The additive composition according to  claim 3 , wherein R′ is a C 1 -C 30  alkyl moiety. 
     
     
         5 . The additive composition according to  claim 3 , wherein the alkyl carboxylate moiety(-ies) are independently chosen from C 1 -C 30  alkyl carboxylate moieties. 
     
     
         6 . The additive composition according to  claim 1 , wherein the 2,5-dimercapto-1,3,4-thiadiazole alkyl (poly)carboxylate compound has the following formula (V): 
       
         
           
           
               
               
           
         
       
     
     
         7 . The additive composition according to  claim 1 , wherein
 the weight ratio between the organomolybdenum compound and the 2,5-dimercapto-1,3,4-thiadiazole alkyl (poly)carboxylate compound ranges from 1:100 to 100:1.   
     
     
         8 . A lubricant composition comprising:
 at least one base oil; and   at least one additive composition as defined in  claim 1 .   
     
     
         9 . The lubricant composition according to  claim 8 , comprising from 50% to 99.5% by weight of base oil relative to the total weight of the lubricant composition. 
     
     
         10 . The lubricant composition according to  claim 9 , wherein the content of elemental molybdenum ranges from 50 to 1,500 ppm by weight, compared to the total weight of the lubricant composition. 
     
     
         11 . The lubricant composition according to  claim 9 , comprising from 0.2% to 1.0% by weight of 2,5-dimercapto-1,3,4-thiadiazole, alkyl (poly)carboxylate compound, compared to the total weight of the lubricant composition. 
     
     
         12 . The lubricant composition according to  claim 9 , having a sulphur content ranging from 0.01% to 5% by weight, compared to the total weight of the composition. 
     
     
         13 . A method of maintaining over time the fuel economy properties of a lubricating composition comprising at least one base oil and an organomolybdenum compound, said method comprising the addition to said lubricating composition of a 2,5-dimercapto-1,3,4-thiadiazole alkyl (poly)carboxylate compound. 
     
     
         14 . (canceled) 
     
     
         15 . The method according to  claim 13 , wherein the organomolybdenum compound is chosen from dinuclear organomolybdenum compounds. 
     
     
         16 . The additive composition according to  claim 1 , wherein the organomolybdenum compound is chosen from molybdenum dithiocarbamates. 
     
     
         17 . The additive composition according to  claim 4 , wherein R′ is a C1-C20 alkyl moiety. 
     
     
         18 . The additive composition according to  claim 17 , wherein R′ is a C1-C10 alkyl moiety. 
     
     
         19 . The additive composition according to  claim 18 , wherein R′ is an ethyl moiety. 
     
     
         20 . The additive composition according to  claim 5 , wherein the alkyl carboxylate moiety(-ies) are independently chosen from C1-C20 alkyl carboxylate moieties. 
     
     
         21 . The additive composition according to  claim 20 , wherein the alkyl carboxylate moiety(-ies) are 2-ethylhexyl carboxylate moieties.