Home - engines - Ford Diesel Engines | Engine Oil Specifications Ford Diesel Engines | Engine Oil Specifications Home › Engines › Ford Ford Diesel Engines Ford diesel engines. Oil specifications, viscosity grades, and drain intervals for the 6.7L Power Stroke. Engine Pages 6.7L 6.7L Power Stroke API CK-4. 10W-30 or 5W-40. Motorcraft spec. View spec → CK-4 vs FA-4Best oil for semi trucks