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.
Claims18
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 0.2 to 0.72, 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 1.0:1 to 1.12:1.
A medium or heavy-duty diesel engine comprising:
- a diesel engine crankcase configured for powering a vehicle weighing at least about 14,000 pounds, and wherein the medium or heavy-duty diesel engine includes an exhaust gas recirculation system;
- a lubricant for the diesel engine crankcase including (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 secondary alcohols or combinations of secondary and primary alcohols, wherein the hydrocarbyl groups have an average degree of branching of 0.2 to 0.72, 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;
- and wherein the one or more overbased zinc dihydrocarbyl dithiophosphate compounds of the antiwear system herein have a zinc to phosphorous ratio of 1.0:1 to 1.12:1.
Dependencies are inferred from the claim text.