It depends on the specifications the diesel oil carries and the recommendation of the original equipment manufacturer (OEM). The American Petroleum Institute (API) publishes its “C” category of specifications for diesel oil (currently CK-4) and its “S” category for gasoline motor oil (currently SP).

You can use diesel oil in a gas engine provided the diesel oil meets the appropriate specifications and viscosity requirements of your engine. For example, if your gas engine calls for a 5W-30 motor oil that meets the API SN specification, you can safely use a diesel oil of the correct viscosity that meets the API SN spec. For the typical gasoline application, however, a diesel oil isn’t required, and the more appropriate choice is a quality gasoline motor oil for both performance and value.

Why do diesel engines need specific oil?

Outside of differences in the fuel, the most notable difference between diesel and gas engines is the way each ignites the fuel. Diesel engines compress air in the combustion chamber until the temperature of the air increases enough to ignite the fuel (sprayed into the combustion chamber by the injector). Gasoline engines, on the other hand, use spark plugs that ignite a mixture of fuel and air at just the right time.

Diesel oil is formulated differently than gasoline oil in order to address issues specific to diesel engines, including higher engine temperatures, oxidation rates, soot levels and deposits. Find the best AMSOIL synthetic diesel oil for your application in the Product Lookup. AMSOIL diesel fuel additives also provide benefits designed to keep diesel engines operating at top performance.

How often should you perform a diesel oil change?

Refer to the vehicle owner’s manual for specific oil-change recommendations. AMSOIL synthetic diesel oils may be used beyond the OEM-recommended interval based on the service-life recommendations on the data sheets or with oil analysis. In addition, AMSOIL offers a full line of premium synthetic gear oil and transmission fluid to keep your diesel running at peak performance.