Mercury Quicksilver 25W-50 4-Stroke Synthetic Blend Marine Engine Oil Gallon. Recommended for use in Mercury Verado and other high performance marine engines. Provides outstanding wear and corrosion protection to help extend engine life. Meets or exceeds all marine engine manufacturer's warranty requirements and recommendations for use of an FC-W marine engine oil. It maintains its viscosity, protects against varnish buildup and sludge formation and exceeds the rust protection requirements for NMMA certification. See your owner's manual or service manual for specific applications and instructions.