Lubricant compositions having improved oxidation performance

Abstract

Disclosed are lubricant compositions with improved oxidation stability which are prepared with Group III base stocks comprising greater than or equal to about 90 wt. % saturated hydrocarbons (saturates); a viscosity index from 120 to 145; a unique ratio of molecules with multi-ring naphthenes to single ring naphthenes (2R+N/1RN); a unique ratio of branched carbons to straight chain (BC/SC) carbons; and a unique ratio of branched carbons to terminal chain (BC/TC) carbons.

1 . A lubricating composition comprising:
 a Group III base stock comprising at least 90 wt. % saturated hydrocarbons, the Group III base stock having a kinematic viscosity at 100° C. (KV100) of 4.0 cSt to 12.0 cSt, a viscosity index of from 120 to 133, and a ratio of multi-ring naphthenes to single ring naphthenes (2R+N/1RN) of less than 0.43; and   an effective amount of one or more lubricant additives;   wherein the lubricating composition has an oxidation induction time greater than 120 minutes.   
     
     
         2 . The composition of  claim 1 , wherein the base stock has a KV100 of from 4.0 cSt to 5.0 cSt. 
     
     
         3 . The composition of  claim 1 , wherein the base stock has a KV100 is from 5.0 cSt to 7.0 cSt. 
     
     
         4 . The composition of  claim 2 , wherein the viscosity index is 120 to 133 and is less than or equal to 142*(1−0.0025 exp(8*(2R+N/1RN))). 
     
     
         5 . The composition of  claim 3 , wherein the viscosity index is 120 to 133 and is less than or equal to 150.07*(1−0.0106*exp(4.5*(2R+N/1RN))). 
     
     
         6 . An engine oil composition comprising:
 a Group III base stock, the Group III base stock having at least 90 wt. % saturated hydrocarbons, kinematic viscosity at 100° C. of from 4.0 cSt up to 5.0 cSt, a viscosity index of from 120 to less than 140, and a ratio of multi-ring naphthenes to single ring naphthenes (2R+N/1RN) of less than 0.45; and   an effective amount of one or more lubricant additives;   wherein the oil composition has an oxidation induction time greater than 120 minutes.   
     
     
         7 . The composition of  claim 6 , wherein the viscosity index is 102 to 140 and is less than or equal to 142*(1−0.0025 exp(8*(2R+N/1RN))). 
     
     
         8 . A heavy duty diesel engine lubricating oil composition comprising:
 a Group III base stock, the Group III base stock having at least 90 wt. % saturated hydrocarbons, a kinematic viscosity at 100° C. of from 5.5 cSt up to 7.0 cSt, a viscosity index of from 120 to less than 144; and a ratio of multi-ring naphthenes to single ring naphthenes (2R+N/1RN) of less than 0.56; and   an effective amount of one or more lubricant additives;   wherein the lubricating oil composition has an oxidation induction time greater than 120 minutes.   
     
     
         9 . The composition of  claim 8 , wherein the viscosity index is 120 to 144 and is less than or equal to 142*(1−0.0025 exp(8*(2R+N/1RN))). 
     
     
         10 . A lubricating composition comprising:
 a Group III base stock having at least 90 wt. % saturated hydrocarbons, a kinematic viscosity at 100° C. of 4.0 cSt to 5.0 cSt, a viscosity index of 120 to 140, and a ratio of multi-ring naphthenes to single ring naphthenes (2R+N/1RN) of less than 0.52; and a ratio of branched carbons to straight chain carbons (BC/SC) less than or equal to 0.21; and   an effective amount of one or more lubricant additives;   wherein the lubricating composition has an oxidation induction time greater than 120 minutes.   
     
     
         11 . The lubricating composition of  claim 10 , wherein the base stock has a ratio of branched chain carbons to terminal carbons (BC/TC) less than or equal to 2.1. 
     
     
         12 . A lubricating composition comprising:
 a Group III base stock having:
 at least 90 wt. % saturated hydrocarbons; 
 kinematic viscosity at 100° C. of 5.0 cSt to 12.0 cSt; 
 a viscosity index of 120 to 140; 
 a ratio of multi-ring naphthenes to single ring naphthenes (2R+N/1RN) of less than 0.59; and a ratio of branched carbons to straight chain carbons (BC/SC) less than or equal to 0.26; and 
   an effective amount of one or more lubricant additives;   wherein the lubricating composition has an oxidation induction time greater than 120 minutes.   
     
     
         13 . The lubricating composition of clause 12, wherein the base stock has a ratio of multi-ring naphthenes to single ring naphthenes (2R+N/1RN) of less than 0.59 and BC/TC≤2.3. 
     
     
         14 . A lubricating composition comprising:
 a Group III base stock comprising:
 at least 90 wt. % saturated hydrocarbons; 
 kinematic viscosity at 100° C. (KV100) of 4.0 cSt to 5.0 cSt; 
 a viscosity index of from 120 to 140; and 
 a ratio of multi-ring naphthenes to single ring naphthenes (2R+N/1RN) of less than 0.45; and 
 an effective amount of one or more lubricant additives; 
   wherein the lubricating composition has an oxidation induction time greater than 120 minutes.   
     
     
         15 . The composition of  claim 14 , wherein the base stock KV100 of 4.0 to 4.7. 
     
     
         16 . A lubricating composition comprising a Group III base stock having:
 at least 90 wt. % saturated hydrocarbons;   kinematic viscosity at 100° C. (KV100) of 5.0 cSt to 12.0 cSt;   a viscosity index of from 120 to 144;   a ratio of multi-ring naphthenes to single ring naphthenes (2R+N/1RN) of less than 0.56; and   an effective amount of one or more lubricant additives;   wherein the lubricating composition has an oxidation induction time greater than 120 minutes.   
     
     
         17 . The composition of  claim 16 , wherein the base stock KV100 of 5.5 to 7.0.