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.