Yamaha's 10W-40 Mineral 4W WaterCraft All Purpose Engine Oil, known as Yamalube 4W, is a motor oil specifically formulated to meet the demanding conditions of the marine environment. Designed for high-revving four-stroke WaveRunner and Yamaha Boat engines, this oil delivers outstanding anti-corrosion and anti-wear performance where it matters most. Its proprietary blend includes marine-specific anti-wear additives, shear-stable polymers, corrosion inhibitors, detergents, dispersants, and viscosity index improvers, providing protection that goes well beyond what standard automotive engine oils can offer. Whether your engine faces cold starts, extended hours of trolling, or high-load, high-speed operation, Yamalube 4W is engineered to keep it running smoothly and reliably. The special anti-corrosive additives are particularly suited to withstand the harsh saltwater and freshwater marine environments. Available in both quart and gallon sizes, this mineral-based engine oil is the trusted choice for boaters who demand superior durability, strength, and corrosion resistance for their watercraft engines.