Lube Advisor

Sinclair Monograde Heavy Duty Diesel Engine Oil

Heavy Duty Engine Oil

Sinclair Monograde Heavy Duty Engine Oil has been formulated to provide outstanding protection for older engines. With proper care, older engines can keep you up and running for many more miles, and that proper care starts with Sinclair Heavy-Duty Diesel Engine Oils that meet or exceed the recommendations of engine manufacturers.

Advanced Oils for Engines of Advanced Age

Your engine has served you well over the years. Now it’s your turn to serve it with outstanding protection that strikes just the right mix of durability, longer drain intervals and protection of emissions control devices.

Sinclair Monograde Heavy Duty Diesel Engine Oil: Performance You'll Notice

Sinclair leans on over 100 years of lubrication knowledge to bring you a tough, enduring level of protection that reduces contact between metal parts and keeps friction at a minimum, giving you:


Outstanding performance for extended drain intervals, with up 1.6% improved fuel mileage with HD 10W-30 grade.


Increased wear protection of up to 53%.


Deposit control up to 63% and better oxidation control up to 83%.

Sinclair Monograde Heavy Duty Diesel Engine Oil

Sinclair SAE 30 Heavy Duty Diesel Engine Oil

For older diesel engines.

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