Marine diesel lubricant oil compositions having improved low temperature performance

Abstract

A method for improving low temperature performance of a lubricant in a compression-ignited internal combustion engine is disclosed. The method comprises operating the engine with a monograde lubricating oil composition comprising (a) a major amount of a base oil of lubricating viscosity; and (b) a minor amount of an overbased alkaline earth metal salt of an alkyl-substituted hydroxyaromatic compound, the alkyl substituent being a residue derived from an isomerized alpha-olefin having from 12 to 40 carbon atoms per molecule.

1 . A method for improving low temperature performance of a lubricant in a compression-ignited internal combustion engine, the method comprising operating the engine with a lubricating oil composition comprising (a) greater than 50 wt. % of a base oil of lubricating viscosity; and (b) 0.1 to 40 wt. % of an overbased alkaline earth metal salt of an alkyl-substituted hydroxyaromatic compound, wherein the alkyl substituent is a residue derived from an isomerized alpha-olefin having from 12 to 40 carbon atoms per molecule; wherein the lubricating oil composition is a monograde lubricating oil composition meeting specifications for SAE J300 revised January 2015 requirements for a SAE 20, 30, 40, 50, or 60 monograde engine oil, and has a TBN of 5 to 200 mg KOH/g, as determined by ASTM D2896. 
     
     
         2 . The method of  claim 1 , wherein the alkyl-substituted hydroxyaromatic compound is an alkyl-substituted phenol, an alkyl-substituted hydroxyaromatic carboxylic acid, or a combination thereof. 
     
     
         3 . The method of  claim 1 , wherein the isomerized alpha-olefin is an isomerized normal alpha-olefin. 
     
     
         4 . The method of  claim 1 , wherein the alkyl substituent of the alkyl-substituted hydroxyaromatic compound is a residue derived from an alpha-olefin having from 14 to 28 carbon atoms per molecule. 
     
     
         5 . The method of  claim 1 , wherein the alkyl substituent of the alkyl-substituted hydroxyaromatic compound is a residue derived from an alpha-olefin having from 20 to 28 carbon atoms per molecule. 
     
     
         6 . The method of  claim 1 , wherein the alkyl substituent of the alkyl-substituted hydroxyaromatic compound is a residue derived from an alpha-olefin having from 20 to 24 carbon atoms per molecule. 
     
     
         7 . The method of  claim 1 , wherein the overbased alkaline earth metal salt of an alkyl-substituted hydroxyaromatic compound has a TBN, on an actives basis, of 100 to 500 mg KOH/g. 
     
     
         8 . The lubricating oil composition of  claim 1 , wherein the lubricating oil composition has a TBN in one of the following ranges: 5 to 10 mg KOH/g, 15 to 150 mg KOH/g, 20 to 80 mg KOH/g, 30 to 100 mg KOH/g, 30 to 80 mg KOH/g, 60 to 100 mg KOH/g, 60 to 150 mg KOH/g. 
     
     
         9 . The method of  claim 1 , wherein the lubricating oil composition further comprises one or more of other detergents, a dispersant, an antiwear agent, an antioxidant, a friction modifier, a corrosion inhibitor, a rust inhibitor, a demulsifier, a foam inhibitor, a viscosity modifier, a pour point depressant, a non-ionic surfactant, and a thickener. 
     
     
         10 . The method of  claim 1 , wherein the compression-ignited internal combustion engine is a 4-stroke engine operated at 250 to 1100 rpm. 
     
     
         11 . The method of  claim 1 , wherein the compression-ignited internal combustion engine is a 2-stroke engine operated at 200 rpm or less. 
     
     
         12 . The method of  claim 1 , wherein the compression-ignited internal combustion engine is fueled with a residual fuel, a marine residual fuel, a low sulfur marine residual fuel, a marine distillate fuel, a low sulfur marine distillate fuel, a high sulfur fuel, or a gaseous fuel. 
     
     
         13 . The method of  claim 1 , wherein low temperature performance is measured according to ASTM D6749.