When it comes to Heavy Duty Motor Oils for both Gasoline and Diesel engines Chevron is the leader of the pack. With two complete lines of heavy duty motor oils, Chevron Delo Series and Chevron RPM Series, Chevron is sure to have the top quality heavy duty motor oil for all of your needs. Both lines of Chevron Heavy Duty Motor Oils are formulated with Chevron's patented Group II Hydrocracked (c) base oils. Chevron has been blending and additizing Group II Base oils for over 18 years. This gives Chevron the advantage over the other brands who are struggling to develop their own Group II base oils in time for the new engines and the exhaust gas recirculation systems that are being installed now to conform with the new government regulations. Don't be a test subject trust Chevron's proven formulations for all of your Heavy Duty Motor Oil needs.