Product Details Keep your 4-stroke outboard protected through long runs, cold starts, and hard fishing days with Star Brite Super Premium Synthetic 10W30 4-Stroke Oil, a marine engine oil that helps bass, walleye, salmon, musky, and saltwater anglers maintain strong performance in demanding freshwater and saltwater conditions. This 1-gallon formula targets 4-stroke outboard motors and also works well in high-performance outboards, gasoline inboards, and stern drives that operate at high RPMs and carry heavy loads. Shear-stable polymer additives and synthetic base stocks help maintain proper viscosity when heat, stress, and long run times push your engine hard, while the synthetic-and-organic blend supports quicker, more reliable starts at low temperatures. Its NMMA FC-W certified formula fights sludge and varnish buildup, improves engine cleanliness, and adds rust and wear protection with anti-wear additives and corrosion inhibitors that help reduce piston deposits and protect against sticking valves and rings. Shear-stable polymer additives and synthetic base stocks support strong protection under high stress and RPMs Synthetic and organic blend helps improve cold starts and maintain viscosity in harsh marine conditions NMMA FC-W certified formula helps prevent sludge, varnish, piston deposits, and sticking valves and rings Works in 4-stroke outboards, high-performance outboards, gasoline inboards, and stern drives in saltwater and freshwater use 1 gallon Made in the USA Prop 65 Warning Customer Reviews Be the first to write a review Write a Review