A leak in your lower unit isn't just an inconvenience-it's a serious threat to your outboard's performance and longevity. The Sierra 18-0554 Oil Seal is designed to keep oil in and water out, ensuring your Yamaha outboard stays properly lubricated and protected from corrosion. Built with high-quality materials, this seal withstands the demanding conditions of marine environments, preventing premature wear and maintaining engine efficiency trip after trip.. Built for Reliable Protection. Prevents Oil Leaks - Creates a tight seal to keep lubrication where it belongs, reducing the risk of internal damage.. Blocks Water Intrusion - Shields gears and bearings from moisture, dirt, and debris, extending the life of essential components.. OEM-Level Fit & Durability - Engineered for Yamaha 20-45 HP outboards, ensuring a precise fit and long-term reliability.. Essential for Routine Maintenance. Replacing a worn oil seal is a simple but crucial step in preventing costly lower unit repairs. Regula