Lubricating oil composition

Abstract

The present invention provides a lubricating oil composition comprising at least one type of base oil selected from mineral oils and synthetic oils, and a succinate ester and a sarcosinic acid as rust prevention agents. The succinate ester content is preferably set at 0.01 to 0.1 wt. %, and the sarcosinic acid content is preferably set at 0.001 to 0.01 wt. %. Further, they are preferably set such that the resulting weight ratio of the succinate ester content and sarcosinic acid content is 1:0.01 to 0.7. The lubricating oil composition according to the present invention shows excellent rust prevention properties and a satisfactorily long oxidation lifetime. Further it allows to attain a high level of anti-sludge performance and extreme pressure performance and lubrication performance, even when it is used for example in turbine bearings in combined cycle generators having multiplier gears operated under severe high temperature and high pressure conditions.

1 .- 12 . (canceled) 
     
     
         13 . A lubricating oil composition comprising:
 a base oil having a kinematic viscosity of 8 to 220 mm 2 /sec at 40° C., a total sulphur content of 0 to 30 ppm, a total nitrogen content of 0 to 30 ppm and an aniline point of 110° C. to 135° C.;   a succinate ester present in an amount of 0.01 to 0.1 wt % relative to the total weight of the lubricating oil composition; and   sarcosinic acid present in an amount of 0.001 to 0.01 wt % relative to the total weight of lubricating oil composition,   wherein the weight ratio of the succinate ester to the sarcosinic acid is 1:0.01 to 0.7.   
     
     
         14 . A lubricating oil composition according to  claim 13 , further comprising at least one type of phosphorus compound. 
     
     
         16 . A lubricating oil composition according to  claim 14  wherein the phosphorus compound is selected from the group consisting of a phosphate ester, acid phosphate ester, acid phosphate ester amine salt, chlorinated phosphate ester, phosphite ester, phosphorothionate, zinc dithiophosphate, dithiophosphate ester or derivative thereof, phosphorus-containing carboxylic acid, phosphorus-containing carboxylate ester, and a mixture thereof. 
     
     
         17 . A method according to  claim 16  wherein the phosphorus-containing carboxylic acid or phosphorus-containing carboxylate ester is β-dithio-phosphorylated propionic acid or a β-dithiophosphorylated propionate ester. 
     
     
         18 . A lubricating oil composition according to  claim 13 , further comprising an aromatic amine compound. 
     
     
         19 . A lubricating oil composition according to  claim 18  wherein the aromatic amine compound is at least one of a phenyl-α-naphthylamine compound or a dialkyldiphenylamine compound.