Emulsifiable Marine Lower Unit Gear Oil

Abstract

A lubricant composition for lower unit gear drives in outboard and stern drive engines is disclosed. The lubricant composition comprises: (a) a highly sulfurized olefin; (b) an amine salt of a phosphorus compound; (c) a high molecular weight PIBSA-PAM dispersant; and (d) a copper corrosion inhibitor.

1 . An additive package for lower unit gear drives in outboard and stern drive engines comprising:
 (a) a highly sulfurized olefin;   (b) an amine salt of a phosphorus compound;   (c) a high molecular weight PIBSA-PAM dispersant having a molecular weight of 2000 or higher; and   (d) a copper corrosion inhibitor.   
     
     
         2 . The additive package according to  claim 1  wherein the highly sulfurized olefin comprises sulfurized isobutylene. 
     
     
         3 . The additive package according to  claim 1  wherein the amine salt of a phosphorous compound comprises a C 12  to C 14  t-alkyl primary amine. 
     
     
         4 . The additive package according to  claim 1  wherein the amine salt of a phosphorus compound is an amine comprising the reaction product of methyl isobutyl carbinol dithiophosphoric acid with propylene oxide. 
     
     
         5 . The additive package according to  claim 1  wherein the amine salt of a phosphorus compound comprises an amine salt of a phosphoric acid ester. 
     
     
         6 . The additive package according to  claim 5  wherein the amine salt of the phosphoric acid ester has a low amine/phosphorus molar ratio. 
     
     
         7 . The additive package according to  claim 1  wherein the ratio of the highly sulfurized olefin to the amine salt of a phosphorus compound is 15:1. 
     
     
         8 . The additive package according to  claim 1  wherein the high molecular weight PIBSA-PAM dispersant is non-borated. 
     
     
         9 . The additive package according to  claim 1  wherein the copper corrosion inhibitor comprises a tolyltriazole compound. 
     
     
         10 . The additive package according to  claim 1  wherein the copper corrosion inhibitor comprises a thiadiazole compound. 
     
     
         11 . A lubricant composition for lower unit gear drives in outboard and stern drive engines comprising:
 (a) a highly sulfurized olefin;   (b) an amine salt of a phosphorus compound;   (c) a high molecular weight PIBSA-PAM dispersant; and   (d) a copper corrosion inhibitor, wherein the lubricant composition is in the lower unit gear drives.   
     
     
         12 . The lubricant composition according to  claim 11  wherein nitrogen from the high molecular weight PIBSA-PAM dispersant is present in an amount ranging from 10 ppm to 500 ppm. 
     
     
         13 . The lubricant composition according to the  claim 1  comprising essentially no heavy metals. 
     
     
         14 . The lubricant composition according to  claim 13  comprising less than or equal to 0.25 weight percent of antimony.