Lucas Extreme Duty Marine Semi Synthetic 20W-50 Engine Oil is manufactured with the highest quality paraffinic base oils and is fortified with an exclusive additive package containing high levels of Zinc, Moly and Phosphorus that provides a tougher, thicker additive film for maximum protection even under the most severe conditions. It lowers oil temperatures, extends oil life and minimizes metal fatigue. It improves the film strength between the cylinder wall and piston rings and slows oil burning while improving pressure levels in worn engines. It has good cold temperature properties and stands up to high operating temperatures. This product is compatible with methanol and all racing fuels.