Quicksilver 4-Stroke FC-W Synthetic Blend Oil 10W-30, For use in all brands & types of 4-stroke marine engines including: Outboards, High Performance, Stern Drives/Inboards, Personal Watercraft Exceeds all Marine industry 4-Stroke oil requirements Flagship Engine and Corrosion Protection - Industry leading strength and viscosity retention and ultimate corrosion and wear protection The most recommended Marine Oil - Over 5 years of engineering and development by the largest marine engine manufacturer in the world.