Detergent and dispersant systems for improved steel piston cleanliness in heavy duty lubricants

Abstract

The present disclosure relates to heavy duty crankcase lubricating oil compositions achieving high piston cleanliness of steel piston pursuant to the OM471 piston cleanliness test using a detergent system of sulfonate soap and dispersant system of one or more polyisobutylene succinimide dispersants to the lubricating oil composition.

What is claimed is: 
     
         1 . A method of lubricating a heavy-duty diesel engine having steel pistons, the method comprising:
 lubricating the steel pistons of the heavy-duty diesel engine with a lubricating oil composition:   wherein the lubricating oil composition includes (i) a detergent system consisting of one or more alkaline earth metal sulfonate detergents delivering from 0.3 to about 1 weight percent sulfonate soap to the lubricating oil composition and (ii) a dispersant system including one or more polyisobutylene succinimide dispersants delivering at least about 5 weight percent of the one or more dispersants to the lubricating oil composition; and   wherein the one or more polyisobutylene succinimide dispersants are derived from highly reactive polyisobutylenes having a number average molecular weight of about 1,200 to about 2,500 and delivering more than 650 ppm nitrogen to the lubricating oil composition.   
     
     
         2 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 1 , wherein the heavy-duty diesel engine is operated under conditions set forth in the OM471 Piston Cleanliness test of CEC L-118-21. 
     
     
         3 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 1 , wherein the heavy-duty diesel engine is configured for powering a vehicle having a gross vehicle weight rating of about 6,000 pounds or higher. 
     
     
         4 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 1 , wherein the detergent system consists of one or more overbased calcium sulfonate detergents and one or more low-based calcium sulfonate detergents, wherein an overbased detergent has a total base number (TBN) of at least about 300 mg KOH/g and a low-base detergent has a total base number (TBN) of about 175 mg KOH/g or less and with total base number (TBN) determined by ASTM D2896. 
     
     
         5 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 4 , wherein the lubricating composition includes about 0.3 to about 0.7 weight percent of sulfonate soap. 
     
     
         6 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 4 , wherein the detergent system includes an effective amount of the one or more overbased sulfonate detergents to provide at least about 5 mg KOH/g to the detergent system and an effective amounts of the one or more low-based sulfonate detergents to provide about 25 to about 40 weight percent of the detergent soap. 
     
     
         7 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 1 , wherein the detergent system consists essentially of calcium sulfonate detergents. 
     
     
         8 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 1 , wherein the detergent system is substantially free of magnesium sulfonate detergents, substantially free of phenate detergents, or combinations thereof. 
     
     
         9 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 1 , wherein the lubricating oil composition includes about 50 ppm to about 200 ppm molybdenum provided by an oil-soluble molybdenum compound selected from the group of molybdenum dithiocarbamates, molybdenum dialkyldithiophosphates, sulfur-free organomolybdenum complexes of organic amides, or mixtures thereof. 
     
     
         10 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 1 , wherein the lubricating oil composition further includes about 0.5 to about 5 weight percent of one or more ashless antioxidants selected from hindered phenols, aromatic amines, alkylated diphenylamines, phenyl-α-napthylamines, alkylated phenyl-α-naphthylamines, hindered non-aromatic amines sulfurized olefins, or mixtures thereof. 
     
     
         11 . The method of lubricating a heavy-duty diesel engine having steel pistons of  claim 1 , wherein the lubricating oil composition includes up to about 1200 ppm of phosphorus from one or more metal dihydrocarbyl dithiophosphate compounds having hydrocarbyl groups derived from a mixture of linear or branched primary alcohols and linear or branched secondary alcohols. 
     
     
         12 . A heavy-duty crankcase lubricating oil composition suitable for a diesel engine having a gross vehicle weight of about 6,000 pounds or more, the heavy-duty crankcase lubricating oil composition comprising:
 one or more base oils of lubricating viscosity:   a detergent system consisting of one or more alkaline earth metal sulfonate detergents delivering up to about 1 weight percent sulfonate soap to the lubricating oil composition:   a dispersant system comprising one or more polyisobutylene succinimide dispersants delivering at least about 5 weight percent of the one or more dispersants to the lubricating composition; and   wherein the one or more polyisobutylene succinimide dispersants are derived from highly reactive polyisobutylenes having a number average molecular weight of about 1,200 to about 2,500 and delivering more than 650 ppm nitrogen to the lubricating oil composition.   
     
     
         13 . The heavy-duty crankcase lubricating oil composition of  claim 12 , wherein the lubricating oil composition achieves a steel piston cleanliness rating of at least about 90% as measured by the OM471 Piston Cleanliness Test (CEC L-118-21). 
     
     
         14 . The heavy-duty crankcase lubricating oil composition of  claim 12 , wherein the detergent system consists of one or more overbased calcium sulfonate detergents and one or more low-based calcium sulfonate detergents, wherein an overbased detergent has a total base number (TBN) of at least about 200 mg KOH/g and a low-base detergent has a total base number (TBN) of about 175 mg KOH/g or less and with total base number (TBN) determined by ASTM D2896. 
     
     
         15 . The heavy-duty crankcase lubricating oil composition of  claim 13 , wherein the detergent system includes an effective amount of the one or more overbased sulfonate detergents to provide at least about 5 mg KOH/g to the detergent system and an effective amounts of the one or more low-based sulfonate detergents to provide about 25 to about 40 weight percent of the detergent soap. 
     
     
         16 . The heavy-duty crankcase lubricating oil composition of  claim 12 , wherein the detergent system consists essentially of calcium sulfonate detergents. 
     
     
         17 . The heavy-duty crankcase lubricating oil composition of  claim 12 , wherein the detergent system is substantially free of magnesium sulfonate detergents, substantially free of phenate detergents, or combinations thereof. 
     
     
         18 . The heavy-duty crankcase lubricating oil composition of  claim 12 , wherein the lubricating oil composition includes about 50 ppm to about 200 ppm molybdenum provided by an oil-soluble molybdenum compound selected from the group of molybdenum dithiocarbamates, molybdenum dialkyldithiophosphates, sulfur-free organomolybdenum complexes of organic amides, or mixtures thereof. 
     
     
         19 . The heavy-duty crankcase lubricating oil composition of  claim 12 , wherein the lubricating oil composition further includes about 0.5 to about 5 weight percent of one or more ashless antioxidants selected from hindered phenols, aromatic amines, alkylated diphenylamines, phenyl-α-napthylamines, alkylated phenyl-α-naphthylamines, hindered non-aromatic amines sulfurized olefins, or mixtures thereof. 
     
     
         20 . The heavy-duty crankcase lubricating oil composition of  claim 1 , wherein the lubricating oil composition includes up to about 1200 ppm of phosphorus from one or more metal dihydrocarbyl dithiophosphate compounds having hydrocarbyl groups derived from a mixture of linear or branched primary alcohols and linear or branched secondary alcohols.