Quicksilver's 4‑Stroke oil technology outperforms automotive oils in marine applications because of its specialized additive package designed for marine engines.. For use in all 4‑Stroke Marine Engines ‑New formula 4‑Stroke oils are engineering approved for all marine 4‑Stroke applications, including Outboard, MerCruiser, High Performance, Stern Drive/Inboard, and exceeds all Marine industry 4‑Stroke oil requirements including FC‑W and FC‑W Catalyst Compatible.. Flagship Engine and Corrosion Protection ‑Industry leading strength and viscosity retention and ultimate corrosion and wear 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.