Oxidation stable gear oil compositions

Abstract

A gear oil lubricant composition and method of operating a vehicle with the composition. The composition may include a first olefinic lubricant having a viscosity ranging from about 80 centistokes to about 150 centistokes at 100° C. and a second olefinic lubricant having a viscosity ranging from about 2 centistokes to about 15 centistokes at 100° C. A ratio of the first olefinic lubricant to the second olefinic lubricant may range from about 2:1 to about 8:1. Additionally, the composition may include an alkylated naphthalene base oil, a boronated ashless dispersant, at least one hindered phenol antioxidant, at least one alkylated diphenylamine antioxidant, and a gear oil additive package having an active phosphorus content of less than about 700 ppm and an active sulfur content of less than about 3 wt. %. The gear oil lubricant composition may contain less than about 0.1 percent by weight antioxidant composition based on a total weight of the lubricant composition.

1 . A gear oil lubricant composition comprising: 
 a first olefinic lubricant having a viscosity ranging from about 80 centistokes to about 150 centistokes at 100° C.;    a second olefinic lubricant having a viscosity ranging from about 2 centistokes to about 15 centistokes at 100° C., wherein a ratio of the first olefinic lubricant to the second olefinic lubricant ranges from about 2:1 to about 8:1;    an alkylated naphthalene base oil;    a boronated ashless dispersant;    an antioxidant composition comprising at least one hindered phenol antioxidant and at least one alkylated diphenylamine antioxidant; and    a gear oil additive package having an active phosphorus content of less than about 700 ppm and an active sulfur content of less than about 2.5 wt. %, wherein the gear oil lubricant composition contains less than about 0.1 percent by weight antioxidant composition based on a total lubricant composition.    
     
     
         2 . The gear oil lubricant composition of  claim 1 , wherein the gear oil additive package comprises an extreme pressure agent, an antiwear agent, a rust inhibitor, a corrosion inhibitor, a defoamer, and a process oil.  
     
     
         3 . The gear oil lubricant composition of  claim 1 , further comprising a seal swelling agent.  
     
     
         4 . The gear oil lubricant composition of  claim 1 , wherein the composition contains from about 100 to about 700 ppm active nitrogen atoms.  
     
     
         5 . The gear oil lubricant composition of  claim 1 , wherein the ashless dispersant comprises a hydrocarbyl substituted succinimide.  
     
     
         6 . The gear oil lubricant composition of  claim 5 , wherein the ashless dispersant comprises a boronated/phosphorylated ashless dispersant.  
     
     
         7 . The gear oil lubricant composition of  claim 1 , wherein the first and second olefinic lubricant comprises oligomers of alphaolefins.  
     
     
         8 . A vehicle axle containing the gear oil lubricant of  claim 1 .  
     
     
         9 . A heavy duty gear oil lubricant composition comprising: 
 a first olefinic lubricant having a viscosity ranging from about 80 centistokes to about 150 centistokes at 100° C.;    a second olefinic lubricant having a viscosity ranging from about 2 centistokes to about 15 centistokes at 100° C., wherein a ratio of the first olefinic lubricant to the second olefinic lubricant ranges from about 2:1 to about 8:1;    an alkylated naphthalene base oil;    a boronated ashless dispersant;    an antioxidant composition comprising at least one hindered phenol antioxidant and at least one alkylated diphenylamine antioxidant; and    a conventional gear oil additive package;    wherein the gear oil lubricant composition has a reactive amine content of less than about 100 to about 400 ppm based on an active nitrogen content of the lubricant composition.    
     
     
         10 . The gear oil lubricant composition of  claim 9 , wherein the gear oil additive package comprises an extreme pressure agent, an antiwear agent, a rust inhibitor, a corrosion inhibitor, a defoamer, and a process oil.  
     
     
         11 . The gear oil lubricant composition of  claim 9 , further comprising a seal swelling agent.  
     
     
         12 . The gear oil lubricant composition of  claim 9 , wherein the composition has an active sulfur content ranging from about 1 wt. % to about 3 wt. % and an active phosphorus content ranging from about 250 to about 700 ppm.  
     
     
         13 . The gear oil lubricant composition of  claim 9 , wherein the ashless dispersant comprises a hydrocarbyl substituted succinimide.  
     
     
         14 . The gear oil lubricant composition of  claim 13 , wherein the ashless dispersant comprises a boronated/phosphorylated ashless dispersant.  
     
     
         15 . The gear oil lubricant composition of  claim 9 , wherein the first and second olefinic lubricant comprises oligomers of alphaolefins.  
     
     
         16 . A vehicle axle containing the gear oil lubricant of  claim 9 .  
     
     
         17 . A thermally stable gear oil lubricant composition, comprising: 
 a first olefinic lubricant having a viscosity ranging from about 80 centistokes to about 150 centistokes at 100° C.;    a second olefinic lubricant having a viscosity ranging from about 2 centistokes to about 15 centistokes at 100° C., wherein a ratio of the first olefinic lubricant to the second olefinic lubricant ranges from about 2:1 to about 8:1;    an alkylated naphthalene base oil;    a boronated ashless dispersant;    an antioxidant composition comprising at least one hindered phenol antioxidant and at least one alkylated diphenylamine antioxidant; and    a conventional gear oil additive package;    wherein, with respect to thermal stability, the lubricant composition has a carbon varnish rating of greater than about 7.4 and a sludge rating of greater than about 9.3 after an L60-1 oxidative stability test of about 300 hours.    
     
     
         18 . The gear oil lubricant composition of  claim 17 , wherein the lubricant composition has a viscosity rise of less than about 100%.  
     
     
         19 . The gear oil lubricant composition of  claim 17 , wherein the gear oil additive package comprises an extreme pressure agent, an antiwear agent, a rust inhibitor, a corrosion inhibitor, a defoamer, and a process oil.  
     
     
         20 . The gear oil lubricant composition of  claim 17 , further comprising a seal swelling agent.  
     
     
         21 . The gear oil lubricant composition of  claim 17 , wherein the composition has an active sulfur content ranging from about 1 wt. % to about 3 wt. % and an active phosphorus content ranging from about 300 to about 700 ppm.  
     
     
         22 . The gear oil lubricant composition of  claim 17 , wherein the ashless dispersant comprises a hydrocarbyl substituted succinimide.  
     
     
         23 . The gear oil lubricant composition of  claim 22 , wherein the ashless dispersant comprises a boronated/phosphorylated ashless dispersant.  
     
     
         24 . The gear oil lubricant composition of  claim 17 , wherein the first and second olefinic lubricant comprises oligomers of alphaolefins.  
     
     
         25 . A vehicle axle containing the gear oil lubricant of  claim 17 .  
     
     
         26 . A method of operating a vehicle containing a drive axle, comprising providing as a lubricant for the drive axle a composition containing: 
 a first olefinic lubricant having a viscosity ranging from about 80 centistokes to about 150 centistokes at 100° C.;    a second olefinic lubricant having a viscosity ranging from about 2 centistokes to about 15 centistokes at 100° C., wherein a ratio of the first olefinic lubricant to the second olefinic lubricant ranges from about 2:1 to about 8:1;    an alkylated naphthalene base oil;    a boronated ashless dispersant;    an antioxidant composition comprising at least one hindered phenol antioxidant and at least one alkylated diphenylamine antioxidant; and    a conventional gear oil additive package;    wherein the lubricant composition has an oxidation stability in a 300 hour L60-1 oxidative stability test that provides a viscosity increase of less than about 100%, a carbon varnish rating of greater than about 7.4 and a sludge rating of greater than or equal to 9.3.    
     
     
         27 . The method of  claim 28  wherein the vehicle is operated in an environment having a temperature of greater than about 40° C.  
     
     
         28 . The method of  claim 28  wherein the vehicle is operated for a distance of more than about 30,000 kilometers between lubricant drain intervals.  
     
     
         29 . The method of  claim 28  wherein the axle is an axle of a heavy duty truck vehicle.  
     
     
         30 . The method of  claim 29  wherein the heavy duty truck vehicle can pull combined loads in excess of 25 metric tons.