Mercury - 10W-30 Mineral Base Oil Four-Stroke Engine Oil 92-8M0078626. Overview. This 10W-30 mineral oil is a straightforward option for anyone running a four-stroke marine engine. It gives the motor the basic protection it needs-good wear control, solid corrosion resistance-and it holds up well through long days on the water. Most folks use it for routine oil changes when they just want something dependable without overthinking it. It comes in a one-gallon jug, which is usually enough for a sta