Mercury 10W-30 4-Stroke Full Synthetic Marine Engine Oil Quart. It's the toughest, strongest engine oil from the performance experts at Mercury. An advanced full synthetic formula includes 49% more anti-wear additives, 45% more dispersants and 24% more detergents than the Mercury 10W-30 synthetic blend formula. That translates to outstanding protection against corrosion, build-up and wear. Elevated levels of ZDDP and a unique multi-grade formula enhance shear resistance to help ensure outstanding performance across the broadest range of temperatures and operating conditions. Use 10W-30 Full Synthetic in non-catlyzed 4-stroke outboards, sterndrives and inboard engines.