Marine engines have to withstand corrosion, moisture, wet environments, wet exhaust and believe or not lower coolant temps. A marine engine can't burn off the excess contaminants left over like an automobile can. The constant jarring from landing daily on top of waves can be an issue causing the oil to bubble creating thinner oil. A good Marine oil has a thick film to protect the engine in between changes. ProPride is committed to giving you world class service, whether its an engine part or oil viscosity, water pump or trim motors our marine experts make finding the right part easy.