15W40 Diesel Engine Oil 55-gallon drum (Conventional Heavy Duty) (DEO), is designed and formulated to provide superior performance. It is suitable for virtually all modern low-emission heavy-duty engines and older hard-working diesel engines. With its wide range of specifications and approvals from many of the world’s leading engine makers, it is an excellent choice for on-highway fleets, general haul, construction, agriculture, public-transport operators, and diesel pick-up trucks. 15W40 Heavy Duty Diesel Engine Oil