Best Oil for 6.7 Cummins: Keep Your Engine Running Smoothly

Keep your engine running at peak efficiency with our picks for the best oil for Cummins engines

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  • Product Network

    17 Products

  • Clock

    18 Hours

  • Reviews

    15 Reviews

How We Decided

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PUBLISHED ON November 21, 2019

Not all motor oil is made the same. This is especially true for motor oils formulated for diesel engines. Each engine has special requirements that not all motor oils address. Manufacturers perform extensive tests on motor oils to determine the optimum characteristics for their engines so they deliver the best performance. Check out our top picks for the best oil for the 6.7 Cummins engine.

  • Best Overall
    Valvoline Premium Blue 15W40 GEO Motor Oil, 1 Gallon

    Cummins specifically recommends this Valvoline Premium Blue 15W-40 motor oil for engines operating in temperatures above 0 degrees Fahrenheit.


    This oil provides good valve recession protection and has a low ash level. It uses a special formulation called triple dispersant chemistry to improve on industry-standard soot protection requirements. It also excels in deposit protection requirements.


    Bottles in cartons may be improperly sealed, leading to leakage. May not provide much difference in protection factors over less-expensive oils.

  • Best Value
    Cummins Onan SAE 15W-40 Oil - 1 Quart

    This oil is formulated to Cummins’ specifications to reduce consumption and engine wear caused by high temperatures.


    Formulation fights viscosity breakdown. It is factory tested to ensure that it meets Cummins requirements. Resists oxidation and reduces engine wear.


    Only available in 1-quart bottles. This oil is more expensive than other approved oils.

  • Honorable Mention
    Valvoline Premium Blue Extreme SAE 5W-40 Synthetic Motor Oil

    Cummins specifically recommends this motor oil for the Cummins 6.7 engine that operates in temperatures below 0 degrees Fahrenheit.


    This motor oil has been extensively tested and proven to extend valve train life as well as low oil consumption and deposit control. Formulated for extremely low temperatures.


    The bottles may be improperly sealed, causing leakage during shipment. It’s a bit pricey and may not last as long as some other brands.

Why Trust Us

All of our reviews are based on market research, expert input, and practical experience with each product we include. This way, we offer genuine, accurate guides to help you find the best picks.

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  • Always check your owner’s manual for the recommended oil for Cummins 6.7 engines. If you don’t go with the recommended oils, make sure the oil you choose meets or exceeds certain American Petroleum Institute (API) and National Institute for Automotive Service Excellence (ASE) standards.
  • Oils are carefully formulated to operate in specific temperature ranges. Buy the proper weight for your environment and season. A lower first number is a thinner base oil for extremely cold temperatures. 
  • Be careful when changing your oil to not over or under fill your Cummins engine. Too much oil in the crankcase/oil pan can create excess pressure, which can push oil past seals and cause damage. 
  • When changing your oil, it’s is a great time to change the air and fuel filters as well. Clean air and fuel filters will help your engine run more efficiently and cleanly, giving you better mileage. 


Q: What weight oil should be used in a 6.7 Cummins engine?

A: Cummins specifically recommends two Valvoline oils for its engines. The 15W-40 oil is for temperatures above 0 degrees Fahrenheit while the 5W-40 is for extremely cold temperatures. 

Q: Are synthetic oils better for 6.7 Cummins engines?

A: That’s open for debate. Some manufacturers and engine builders state that synthetics are better, while others prefer blends. What is universal is that the colder the environment, the lighter weight the oil needs to be to reduce wear during cold starts. 

Q: Is Valvoline Premium a good motor oil for 6.7 Cummins engines?

A: Valvoline Premium Blue and Premium Blue Extreme motor oils are specifically recommended by the Cummins factory. Cummins has tested these oils extensively and determined they have characteristics that make them ideal for diesel engines.

Final Thoughts

Our top pick for the Best oil for Cummins 6.7 engines is the Valvoline Premium Blue 15W-40 Heavy Duty Motor Oil, which is specifically called for by the factory for use in temperatures above 0-degree Fahrenheit.

 The Cummins Onan SAE 15W-40 Oil, our best value pick, is also formulated to Cummins factory specifications to deliver optimal performance.