Lucas Synthetic SAE 10W-40 Outboard Engine Oil is formulated especially for the harsh conditions of high speed watercrafts. These outboard engine oils are catalyst compatible and designed for 4-Stroke applications but also work well in Inboards and Personal Water Crafts. Long lasting and safely blends with synthetic & non-synthetic oils, Lucas outboard engine oils are fortified with a special blend of synthetic additives that coat all moving parts to guard against rust and moisture during long periods of storage.