GotQuestions? Lubricants

Q. Can I use the same engine oil in my gasoline and diesel powered vehicles?

April 28, 2014

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A. Even though many if not most heavy duty engine oils claim both the API C or commercial performance category for diesel and S or service category for gasoline engines, there are two factors two consider. Especially in newer gasoline automotive engines, one factor to consider is the viscosity grades used in diesel engines are generally not correct for modern gasoline automotive engines. Secondly, diesel engine oils typically have additive levels that exceed the gasoline engine chemical compatibility limits that are designed to protect the automotive catalytic convertor. Before electing to use on oil or what has been referred to a universal diesel oil, it is highly recommended that you refer to you owner’s manual as there can be warranty implications in newer vehicles. 

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  1. 1. TOM CAPIZZI [ May 05, 2014 @ 10:47AM ]

    I have used Rotella 15w40 engine oil in everything I own for the last 30 years and 30w the previous 16 years. I have no failures or negative experiences to report. My currect vehicle is a 2007 Sierra 1500 WT with 5.3L V8 with 174,000 miles and still gets 21 MPG highway with no engine problems and changed every 7500 miles. I also run 1540 in my 2002 Pontiac GrandAm 2.2L with 120,000 miles still gets 26 MPG with no problems and changed every 5000 miles. Must be me.

  2. 2. Carla [ June 13, 2016 @ 12:50PM ]

    It's kinda 2yrs late since your comment but I want to thank you for sharing "you've used rotella for everything you truck is not diesel and for the past 5 yrs my bf been putting 15 40 rotella I've been so worried. Anyway now I can believe!

  3. 3. Cliff Downing [ September 05, 2016 @ 11:23AM ]

    If one looks at many of the diesel oil jugs, you will see a SL/SM/ or SN rating on top of the CI-4+/CJ-4 ratings. Those SM/SN ratings are for gasoline engines. The newer blends and full syn diesel oils are more than up to the task to us in many gasoline engines. The oil brands do this so that those with mixed fleets can keep their oil stocks to one type and reduce inventory. Myself, I would be a little averse to use using a 15w40 in my gas engines, but I use 10w30 diesel rated oils in many of my gas engine applications. It really has a lot to do with the engine, the climate you are using it in, and what you are using it for. The typical auto/pickup engine probably would be best with a 10w30 year round, and if one was wanting to use a 40w, one of the newer 5w40 diesel oils would be a better idea in colder climates.

  4. 4. mecanicovolf [ December 07, 2016 @ 12:30PM ]

    I'm a golf ? maintenance mechanic and have both gas and diesel fleet. Is Guardiola ETC Diesel Engine Oil With Liquid Titanium SAE 15W-40 alright for gasoline Engines?


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Author Bio

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Mark Betner

Heavy Duty Lubricants Manager

Mark Betner boasts 35 years of experience in the lubricants business. As the Heavy Duty Product Manager for CITGO Lubricants he is responsible for initiating and implementing the marketing of new products and human development programs and oversees communications with the media, trade shows and consumer education.

Prior to this, he was a field sales manager and technical training administrator at an independent lubricant company specializing in heavy equipment lubrication.

Mark earned a master’s and bachelor’s degree in both chemistry and biology from Indiana University. He holds a certification from the Society of Tribologists and Lubrication Engineers and is a member of the Truck Maintenance Council.


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