Mobil 1 - Turbo Diesel Truck - fully synthetic 5W40 - No energy star. API CL-4,SL/CF Meets API CL-4 Plus/Cl-4/CH-4/CF-4 and ACEA E5/E4/E3 industry standards For gasoline engines - meets the API SL/SJ industry standards This is OK for our Corvair engines? Right? Later, JR