Marine diesel cylinder lubricant oil compositions

Abstract

Disclosed herein are marine diesel cylinder lubricating oil compositions comprising (a) a major amount of one or more Group II basestocks, and (b) a detergent composition comprising (i) one or more alkaline earth metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid having a total base number (TBN) greater than 250, and (ii) one or more high overbased alkyl aromatic sulfonic acids or salts thereof; wherein the aromatic moiety of the alkyl aromatic sulfonic acids or salts thereof contains no hydroxyl groups; and wherein the marine diesel cylinder lubricating oil composition has a TBN of about 5 to about 120.

1 - 20 . (canceled) 
     
     
         21 . A marine diesel cylinder lubricating oil composition comprising
 (a) a major amount of one or more Group II basestocks, and   (b) a detergent composition comprising   (i) 0.1 to 35 wt. % on an actives basis of one or more alkaline earth metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid having a total base number (TBN) greater than 250, based on the total weight of the marine diesel cylinder lubricating oil composition, and   (ii) 0.1 to 34 wt. % on an actives basis of one or more high overbased alkyl aromatic sulfonic acids or salts thereof, based on the total weight of the marine diesel cylinder lubricating oil composition; wherein the aromatic moiety of the alkyl aromatic sulfonic acids or salts thereof contains no hydroxyl groups;   wherein the marine diesel cylinder lubricating oil composition has a TBN of 5 to 120; wherein the one or more high overbased alkyl aromatic sulfonic acids or salts thereof have a TBN of greater than 250; and wherein TBN is measured in accordance with ASTM Standard No. D2896 or an equivalent procedure.   
     
     
         22 . The marine diesel cylinder lubricating oil composition according to  claim 21 , having a TBN of from 20 to 100. 
     
     
         23 . The marine diesel cylinder lubricating oil composition according to  claim 21 , having a TBN of from 10 to 40. 
     
     
         24 . The marine diesel cylinder lubricating oil composition according to  claim 21 , which contains less than 1.5 wt. % of tetrapropenyl phenol (TPP) and its unsulfurized metal salt. 
     
     
         25 . The marine diesel cylinder lubricating oil composition according to  claim 21 , wherein the one or more alkaline earth metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid are one or more calcium salts of an alkyl-substituted hydroxyaromatic carboxylic acid. 
     
     
         26 . The marine diesel cylinder lubricating oil composition according to  claim 21 , wherein the alkyl-substituted moiety of the alkaline earth metal salt of an alkyl-substituted hydroxyaromatic carboxylic acid is a C 10  to C 40  alkyl group. 
     
     
         27 . The marine diesel cylinder lubricating oil composition according to  claim 21 , wherein the one or more alkaline earth metal salts of an alkyl-substituted hydroxyaromatic carboxylic acid have a TBN greater than 250 and up to 800. 
     
     
         28 . The marine diesel cylinder lubricating oil composition according to  claim 21 , wherein the one or more high overbased alkyl aromatic sulfonic acids or salts thereof are one or more high overbased alkaline earth metal alkyl aromatic sulfonates. 
     
     
         29 . The marine diesel cylinder lubricating oil composition according to  claim 21 , wherein the one or more high overbased alkyl aromatic sulfonic acids or salts thereof are one or more high overbased calcium alkyl aromatic sulfonates. 
     
     
         30 . The marine diesel cylinder lubricating oil composition according to  claim 21 , further comprising one or more marine diesel cylinder lubricating oil composition additives selected from the group consisting of an antioxidant, ashless dispersant, detergent, rust inhibitor, dehazing agent, demulsifying agent, metal deactivating agent, friction modifier, pour point depressant, antifoaming agent, co-solvent, corrosion-inhibitor, dyes, extreme pressure agent and mixtures thereof. 
     
     
         31 . The marine diesel cylinder lubricating oil composition according to  claim 21 , which contains less than 0.5 wt. % of any dispersants and/or zinc compounds. 
     
     
         32 . A method for lubricating a marine two-stroke crosshead diesel engine, wherein the method comprises operating the engine with a marine diesel cylinder lubricating oil composition according to  claim 21 . 
     
     
         33 . The use of a marine diesel cylinder lubricating oil composition according  claim 21  for improving high temperature detergency and thermal stability in a two-stroke crosshead marine diesel engine.