Antiwear systems for improved wear in medium and/or heavy duty diesel engines
AssigneeAfton Chemical Corporation
InventorsLeah Donham, Abaigeal Ritzenthaler
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Abstract
The present disclosure relates to lubricating compositions and, in particular, lubricating compositions suitable for medium and/or heavy duty diesel engines having low levels of phosphorus and/or zinc but still achieving good valve train wear by including an antiwear system provided from overbased zinc dihydrocarbyl dithiophosphates having a selected average degree of branching and a certain percent of hydrocarbyl groups derived from secondary alcohols.
Claims20
A medium or heavy duty diesel engine crankcase lubricant to reduce valve train wear, the lubricant comprising:
- one or more base oils of lubricating viscosity;
- an antiwear system providing about 200 to about 500 ppm of phosphorus and/or about 200 to about 500 ppm of zinc from one or more overbased zinc dihydrocarbyl dithiophosphate compounds including hydrocarbyl groups bonded to a phosphorus atom through an oxygen linker;
- wherein the hydrocarbyl groups of the antiwear system are provided from secondary alcohols or combinations of secondary and primary alcohols, wherein the hydrocarbyl groups have an average degree of branching of about 0.2 to about 0.72 and at least about 50 weight percent of the hydrocarbyl groups are derived secondary alcohols, and wherein the hydrocarbyl groups of the antiwear system have an average chain length of 5 to 7 total carbons;
- wherein the one or more overbased zinc dihydrocarbyl dithiophosphate compounds of the antiwear system herein have a zinc to phosphorous ratio of about 1.0:1 to about 1.12:1;
- and
- wherein, when tested according to the Cummins ISB Engine Test (ASTM D7484-21b), the lubricant results in an Average Cam Shaft Wear (ACSW) of 55 μm or lower and/or an Average Tappet Mass Loss (ATWL) of 100 mg or lower.
A method of lubricating a diesel engine to reduce valve train wear, the method comprising:
- lubricating a medium or heavy duty diesel engine with a crankcase lubricant;
- wherein the crankcase lubricant includes (i) one or more base oils of lubricating viscosity and (ii) an antiwear system providing about 200 to about 500 ppm of phosphorus and/or about 200 to about 500 ppm of zinc from one or more overbased zinc dihydrocarbyl dithiophosphate compounds including hydrocarbyl groups bonded to a phosphorus atom through an oxygen linker;
- wherein the hydrocarbyl groups of the antiwear system are provided from primary alcohols, secondary alcohols, or combinations thereof having an average degree of branching of about 0.2 to about 0.72 and at least about 50 weight percent of the hydrocarbyl groups are derived from secondary alcohols, and wherein the hydrocarbyl groups of the antiwear system have an average chain length of 5 to 7 total carbons;
- and wherein the one or more overbased zinc dihydrocarbyl dithiophosphate compounds of the antiwear system herein have a zinc to phosphorus ratio of about 1.0:1 to about 1.12:1,
- wherein the lubrication of the medium or heavy duty diesel engine results in an Average Cam Shaft Wear (ACSW) of 55 μm or lower and/or an Average Tappet Mass Loss (ATWL) of 100 mg or lower in the Cummins ISB Engine Test (ASTM D7484).
Dependencies are inferred from the claim text.