Designed to provide Yamaha owners with precision-blended oil for their Water Vehicle and Sport Boat engines. This formula achieved an exponential reduction in smoke when compared to our previous formula for Water Vehicles. The rust protection package was improved to provide greater parts protection from rust and corrosion. This special formula also significantly reduces wear of engine components, while providing excellent lubrication of moving parts and protecting the engine from ring stick and piston scuffing. Yamalube 2W is the only formula the factory recommends for use in catalytic converter model Water Vehicles. Using other oils can cause serious damage to the catalytic converter. Yamalube 2W may be used in non catalytic converter model Water Vehicles, but must never be used in Yamaha outboards.