With Quicksilver® SAE 25W-40 Synthetic Blend 4-Stroke Marine Engine Oil, your boat's engine will cut waves with the smoothest-running, highest-end performance you've ever experienced. Specifically designed to keep your 4-cycle outboard, sterndrive, or inboard engine running like a charm. Quicksilver delivers superior corrosion protection, which helps lengthens the life of your engine. Not only is it FC-W certified, Quicksilver SAE 25W-40 Synthetic Blend 4-Stroke Marine Engine Oil is the most recommended OEM marine engine oil around.  Delivers smooth-running, high-end performance. Designed for 4-cycle outboards, sterndrives, and inboard engines. Most-recommended OEM marine engine oil. Superior corrosion protection. FC-W certified.