Lubricating oil composition for improved oxidation, viscosity increase, oil consumption, and piston deposit control

Abstract

An engine oil lubricant composition having improved control of oxidation viscosity, and piston deposits is provided. The composition further exhibits performance on the ASTM Sequence IIIG Test of about 90% or less kinematic viscosity increase at 40° C. and about 5.5 or more merits average weighted piston deposits. The composition meets or exceeds the standards of both the ILSAC GF-4 and the General Motors GM4718M specifications.

1 . An engine oil lubricant composition capable of providing improved viscosity increase control and piston cleanliness, wherein the lubricant composition comprises:
 a major amount of a synergistic base oil mixture consisting essentially of at least one Group III base oil, at least one Group IV base oil, and at least one Group V base oil.   
   
   
       2 . The lubricant composition of  claim 1 , wherein the Group III base oil is present in an amount of up to about 50 wt %, the Group IV base oil is present in an amount from about 20 wt % to about 45 wt %, and the Group V base oil is present in an amount from about 5 wt % to about 25 wt % based on the base oil mixture. 
   
   
       3 . The lubricant composition  claim 1 , further comprising a minor amount of an engine oil additive composition. 
   
   
       4 . The lubricant composition of  claim 1 , wherein the composition comprises at least about 250 ppm phosphorus. 
   
   
       5 . The lubricant composition of  claim 1 , wherein the composition is substantially free of a transition metal other than zinc. 
   
   
       6 . The lubricant composition of  claim 5 , wherein the transition metal is selected from the group consisting of titanium and molybdenum. 
   
   
       7 . The lubricant composition of  claim 1 , wherein the composition provides improved oil consumption compared to a lubricant composition comprising a major amount of a base oil consisting of a Group II base oil. 
   
   
       8 . The lubricant composition of  claim 1 , wherein the composition provides improved oil consumption compared to a lubricant composition comprising a major amount of a base oil consisting of a Group III base oil. 
   
   
       9 . The lubricant composition of  claim 1 , wherein the composition provides improved viscosity increase control compared to a lubricant composition comprising a major amount of a base oil consisting of a Group II base oil. 
   
   
       10 . The lubricant composition of  claim 1 , wherein the composition provides improved viscosity increase control compared to a lubricant composition comprising a major amount of a base oil consisting of a Group III base oil. 
   
   
       11 . A method for providing an engine oil lubricant composition capable of achieving an ASTM Sequence IIIG Test kinematic viscosity increase of about 90% or less at 40° C. and average weighted piston deposits having about 5.5 or more merits, comprising combining a Group III base oil, a Group IV base oil, and a Group V base oil into a synergistic base oil mixture. 
   
   
       12 . The method of  claim 11 , wherein the Group III base oil is present in an amount of up to about 50 wt %, the Group IV base oil is present in an amount from about 20 wt % to about 45 wt %, and the Group V base oil is present in an amount from about 5 wt % to about 25 wt % based on the base oil mixture. 
   
   
       13 . The method of  claim 11 , wherein the lubricant composition comprises at least about 250 ppm phosphorus. 
   
   
       14 . The method of  claim 11 , wherein the lubricant composition is substantially free of a transition metal other than zinc. 
   
   
       15 . The method of  claim 14 , wherein the transition metal is selected from the group consisting of titanium and molybdenum. 
   
   
       16 . The method of  claim 11 , wherein the lubricant composition provides improved oil consumption compared to a lubricant composition comprising a major amount of a base oil consisting of a Group II base oil. 
   
   
       17 . The method of  claim 11 , wherein the lubricant composition provides improved oil consumption compared to a lubricant composition comprising a major amount of a base oil consisting of a Group III base oil. 
   
   
       18 . The method of  claim 11 , wherein the lubricant composition provides improved viscosity increase control compared to a lubricant composition comprising a major amount of a base oil consisting of a Group II base oil. 
   
   
       19 . The method of  claim 11 , wherein the lubricant composition provides improved viscosity increase control compared to a lubricant composition comprising a major amount of a base oil consisting of a Group III base oil. 
   
   
       20 . The method of  claim 11 , further comprising combining a minor amount of an engine oil additive composition with a major amount of the base oil mixture. 
   
   
       21 . A method for lubricating an engine component comprising:
 contacting said engine component with a lubricant composition wherein said lubricant composition has an ASTM Sequence IIIG Test kinematic viscosity increase of about 90% or less at 40° C. and average weighted piston deposits having about 5.5 or more merits, and wherein said lubricant composition comprises a major amount of a synergistic base oil mixture of a Group III base oil, a Group IV base oil, and a Group V base oil.   
   
   
       22 . The method of  claim 21 , wherein the Group III base oil is present in an amount of up to about 50 wt %, the Group IV base oil is present in an amount from about 20 wt % to about 45 wt %, and the Group V base oil is present in an amount from about 5 wt % to about 25 wt % based on the base oil mixture. 
   
   
       23 . The method of  claim 21 , wherein the lubricant composition is substantially free of a transition metal other than zinc. 
   
   
       24 . The method of  claim 23 , wherein the transition metal is selected from the group consisting of titanium and molybdenum. 
   
   
       25 . The method of  claim 21 , wherein the lubricant composition comprises at least about 250 ppm phosphorous. 
   
   
       26 . The method of  claim 21 , wherein the lubricant composition provides improved oil consumption compared to a lubricant composition comprising a major amount of a base oil consisting of a Group II base oil. 
   
   
       27 . The method of  claim 21 , wherein the lubricant composition provides improved oil consumption compared to a lubricant composition comprising a major amount of a base oil consisting of a Group III base oil. 
   
   
       28 . The method of  claim 21 , wherein the lubricant composition provides improved viscosity increase control compared to a lubricant composition comprising a major amount of a base oil consisting of a Group II base oil. 
   
   
       29 . The method of  claim 21 , wherein the lubricant composition provides improved viscosity increase control compared to a lubricant composition comprising a major amount of a base oil consisting of a Group III base oil. 
   
   
       30 . The method of  claim 21 , wherein the lubricant composition further comprises a minor amount of an additive composition.