Lubricating Compositions

Abstract

A lubricating composition comprising: (a) a 2 mm 2 /s to about 12 mm 2 /s light neutral base oil; (b) 0 to 20 weight percent of a heavy neutral base oil or a brightstock with a viscosity of above about 12 mm 2 /s to about 40 mm 2 /s; and (c) at least one performance additive comprising: a polymeric thickener, a dispersant, an antiwear agent, a detergent or mixtures thereof, wherein the polymeric thickener when present has a weight average molecular weight (Mw) of more than 8000 and is present in an amount to provide a total viscosity of the composition of about 12 mm 2 /s to about 29 mm 2 /s; the dispersant or detergent when present imparts basicity to said lubricating composition; and the composition has a total base number of at least about 10 mg KOH/g. The invention further provides a method of making the compositions and its use for lubricating an internal combustion engine.

1 . A method of lubricating a cylinder of a 2-stroke marine diesel internal combustion engine with a power output of at least 1600 kilowatts, with a lubricating composition, the method comprising:
 (1) monitoring performance characteristics of the engine;   (2) selecting an additive package to provide a desired TBN level to a lubricating composition to modify the performance characteristics of the engine, wherein the additive package comprises an overbased sulphonate detergent;   (3) combining the additive package of step (2) with (a) a component having a viscosity of about 2 mm 2 /s to 12 mm 2 /s, comprising a light neutral base oil, and optionally (b) a component having a viscosity of above 12 mm 2 /s to about 35 mm 2 /s, comprising heavy neutral base oil or a brightstock, to form a lubricating composition, wherein the light neutral base oil is provided from a new or used crankcase system oil, and wherein the light neutral base oil is present at 50 to 99.9 weight percent of the lubricating composition; and   (4) supplying the lubricating composition of step (3) to the engine;   
       wherein the lubricating composition has a total base number of about 30 or higher mg KOH/g; and wherein the component comprising the light neutral base oil is supplied from an oil reservoir available to said internal combustion engine. 
     
     
         2 . The method of  claim 1 , wherein the internal combustion engine has a power output of at least about 3000 kilowatts. 
     
     
         3 . The method of  claim 1 , wherein the characteristics of the engine comprise wear, engine load, variation in TBN, deposits, or corrosion. 
     
     
         4 . The method of  claim 1 , wherein said reservoir is a day tank or cylinder oil service tank or a storage tank. 
     
     
         5 . The method of  claim 1 , wherein the additive package of step (2) is combined with a base oil in a blender. 
     
     
         6 . The method of  claim 1  wherein the additive package of step (2) further comprises at least one performance additive comprising a polymeric thickener, a dispersant, an antiwear agent, a detergent or mixtures thereof. 
     
     
         7 . The method of  claim 6 , wherein the polymeric thickener comprises polyisobutylene with a weight average molecular weight Mw of more than about 8000 to about 25,000 or a poly(meth)acrylate with a weight average molecular weight Mw of about 20,000 to about 300,000. 
     
     
         8 . The method of  claim 6 , wherein the detergent comprises a sulphonate, a phenate or mixtures thereof. 
     
     
         9 . The method of  claim 6 , wherein the dispersant comprises a polyisobutylene succinimide. 
     
     
         10 . The method of  claim 6 , wherein the antiwear agent comprises a metal hydrocarbyl dithiophosphate. 
     
     
         11 . The method of  claim 1 , wherein the light neutral base oil is present at about 50 to about 99.9 weight percent of the lubricating composition; the heavy neutral base oil or brightstock is present at about 0.01 to about 25 weight percent of the lubricating composition; and at least one performance additive is present at about 0.01 to about 25 weight percent of the lubricating composition. 
     
     
         12 . The method of  claim 1 , wherein the light neutral base oil is present at 60 to 99.9 weight percent of the lubricating composition. 
     
     
         13 . The method of  claim 1 , wherein the light neutral base oil is present at 70 to 99.9 weight percent of the lubricating composition.