Mercury - Quicksilver 10W-30 4-Stroke Marine Oil, 1 Gallon Lubrication 92-8M0078617. Overview. Four-stroke marine engines live a rough life-constant heat, long idle time, sudden throttle changes, and more moisture than any engine really deserves. Clean oil is what keeps them from wearing themselves out. This 10W-30 Quicksilver blend is something a lot of mechanics stick with because it holds steady under load, clings to metal on cold starts, and fights off the corrosion that sneaks into every ma