Lubricating oil composition

Abstract

A method of improving the seal compatibility and/or copper corrosion performance of lubricating oil compositions for the lubrication of the crankcases of an internal combustion engine, which method includes the step of adding to the lubricating oil compositions a minor amount of a non-hydrogenated (unsaturated) olefin polymer. Also described are lubricating oil compositions for engines and transmissions, which compositions contain sulphur and/or a salicylate soap and a minor amount of a non-hydrogenated (unsaturated) polymer, which compositions are compatible with nitrile rubber engine and transmission seals and copper-containing engine and transmission components.

1 . A method of improving copper corrosion properties and/or nitrile seal compatibility in or with a lubricating oil composition comprising a major amount of oil of lubricating viscosity and a minor amount of one or more additives, said composition having a sulfur content of at least 0.1 mass %, based on the total mass of lubricating oil composition, which method comprises adding to and/or incorporating into the lubricating oil composition an effective amount of at least one non-hydrogenated polymer, preferably an olefin polymer or copolymer, such as polybutene and/or polyisobutene.  
   
   
       2 . The method of  claim 1 , wherein said effective amount is from 0.2 to 10.0 mass %, based on the total mass of said lubricating oil composition.  
   
   
       3 . The method of  claim 2 , wherein said effective amount from 1.0 to 2.5 mass %, based on the total mass of said lubricating oil composition.  
   
   
       4 . The method of  claim 1  wherein the oil of lubricating viscosity has a sulfur content of from 0.001 to 0.10 mass %, based on the total mass of oil of lubricating viscosity, and optionally, at least one of the said additives comprises a sulfur-containing compound providing at least 0.005 mass % sulfur, based on the mass of said composition.  
   
   
       5 . The method of  claim 4  wherein the oil of lubricating viscosity has a sulfur content of from 0.005 to 0.05 mass %, based on the total mass of oil of lubricating viscosity, and optionally, at least one of the said additives comprises a sulfur-containing compound providing at least 0.005 mass % sulfur, based on the mass of said composition.  
   
   
       6 . The method of  claim 1 , wherein at least one additive comprising a sulfur-containing compound is selected from metal salts of dihydrocarbyl dithiophosphates, sulfonate detergents, sulfurized phenate detergents, sulfur-containing molybdenum compounds, ashless dithiocarbamates, and combinations thereof.  
   
   
       7 . The method of  claim 1 , wherein said lubricating oil composition has at least one of (a) a sulphated ash (SASH) content of from 0.5 to 1.9 mass and (b) a phosphorus content of less than 1500 ppm, based on the total mass of the composition.  
   
   
       8 . The method of  claim 1 , wherein said lubricating oil composition comprises a salicylate detergent in an amount providing said composition with at least 9 mmoles of salicylate soap per kg of said composition.  
   
   
       9 . The method of  claim 1 , wherein said lubricating oil composition comprises a nitrogen-containing dispersant and/or dispersant-viscosity modifier in an amount providing in said composition from 0.08 to 0.35 mass % of nitrogen.  
   
   
       10 . The method of  claim 1 , wherein said lubricating oil composition has a phosphorus content of less than 1500 ppm, based on the total mass of said composition.  
   
   
       11 . The method of  claim 10 , wherein said lubricating oil composition has a phosphorus content of from 500 to 1500 ppm, based on the total mass of said composition.  
   
   
       12 . The method of  claim 11 , wherein said lubricating oil composition has a phosphorus content of less than 1200 ppm, based on the total mass of said composition.  
   
   
       13 . The method of  claim 12 , wherein said lubricating oil composition has a phosphorus content of from 500 to 1200 ppm, based on the total mass of said composition.  
   
   
       14 . The method of  claim 13 , wherein said lubricating oil composition has a phosphorus content of from 500 to 850 ppm, based on the total mass of said composition.  
   
   
       15 . The method of  claim 1 , wherein said oil of lubricating viscosity comprises at least 50 mass % of mineral oil, based on the total mass of said composition.  
   
   
       16 . The method of  claim 1 , wherein said composition is a power transmission fluid or a crankcase lubricating oil composition for an internal combustion engine.  
   
   
       17 . The method of  claim 16 ,wherein said composition is a crankcase lubricating oil composition for an internal combustion heavy duty diesel (HDD) engine and said composition meets the performance requirements of at least ACEA E2-96#5.  
   
   
       18 . The method of  claim 16 , wherein said composition is a crankcase lubricating oil composition for an internal combustion heavy duty diesel (HDD) engine and meets the performance requirements of at least one of ACEA E7-04 and API CI-4.  
   
   
       19 . The method of  claim 16 , wherein said composition is a crankcase lubricating oil composition for an internal combustion heavy duty diesel (HDD) engine and meets the performance requirements of at least one of ACEA E6-04 and API CJ-4.  
   
   
       20 . The method of  claim 1 , wherein the said non-hydrogenated (co-) polymer has a number average molecular weight in the range of from 450 to 2300.  
   
   
       21 . The method of  claim 20 , wherein the said non-hydrogenated (co-) polymer has a number average molecular weight in the range of from 450 to 1300.  
   
   
       22 . The method of  claim 21 , wherein the said non-hydrogenated (co-) polymer has a number average molecular weight in the range of from 450 to 950.  
   
   
       23 . A lubricating oil composition comprising a sulfur content of at least 0.15 mass %, comprising a major amount of an oil of lubricating viscosity, a minor amount of additive(s) including at least one additive having sulfur content, and a minor amount of a non-hydrogenated olefin polymer, and optionally, one or more of the following: (i) a sulfur-containing additive selected from metal salts of dihydrocarbyl dithiophosphates, sulfonate detergents, sulfurized phenate detergents, sulfur-containing molybdenum compounds, ashless dithiocarbamates, (ii) a sulfated ash (SASH) content of from 0.5 to 1.9 mass % based on the mass of the composition; (iii) a phosphorus content of less than 1500 ppm, (iv) a nitrogen-containing dispersant and/or dispersant-viscosity modifier providing from 0.08 to 0.35 mass % nitrogen in said composition; and (v) a salicylate detergent providing at least 9 mmols of salicylate soap per kilogram of composition.