Automotive and marine engines are engineered to run quite differently. In order to meet emissions and fuel economy standards, automotive engines are calibrated to run within a certain RPM range and seldom see any heavy loads. Most of the time they are running at low RPM, “cruising” down the road, and since the vehicle is rolling they are under a relatively light load. They also run at a controlled temperature to insure consistent operation and fuel usage.
Marine engine oils have to handle high RPM and constant loads experienced by marine engines. Marine engines typically operate at either idle or wide-open throttle. Many marine engines are cooled by lake, river or sea water so, while thermostatically-controlled, their temperature cycling is much different, and fuel dilution can be an issue. A marine engine oil has to resist shear, moisture and corrosion more than an automotive engine oil, and has to have extremely strong film strength to protect engine parts under constant stress and load. Finally, marine engines often go past their oil change window, so anti-oxidants are critical to extending oil lifespan.
Engine configuration in outboard applications is much different than in an automotive application, with the engine often configured vertically. The job of an oil in a vertically-oriented engine is even more challenging because it has to flow up and down while providing consistent protection throughout the engine. Lubricating cylinders and bearings at the top of the engine can be more difficult, and even lubricating individual cylinders, crankshaft and rod bearing journals can be challenging.
Because marine engine oils have to protect against so many marine-specific things (corrosion, oxidation, shear, moisture) additives are much more important in a marine oil blend than in an automotive blend. Marine blends typically contain 20-35-percent additives, while automotive blends contain about 10-20-percent additives. Quicksilver marine engine oils contain significant amounts of anti-wear additives that help protect marine engines from wear that can result from excessive loads and the challenges brought on by their configuration.
Automotive engine oils have a pretty easy job compared to marine engine oils. They are blended for mileage, emissions and efficiency and are not suitable for use in marine engines. Quicksilver Marine Engine Oils are tested and proven to protect against rust and corrosion, offer increased wear protection and have optimum viscosity retention. They have also been tested and proven to protect marine engines better than leading automotive engine oils.