Posted by Lighthouse Marine Supply on Nov 26th 2025
Winter Marine Engine Maintenance: Tips to Extend Engine Life
Proper winter maintenance is crucial for protecting your marine engine and ensuring a smooth start next boating season. Here’s a practical guide covering oil, cooling, fuel, and electrical systems to help extend the life of your engine.
Oil System: Change and Protect
- Change the oil & filter: Old oil contains acids and contaminants that can damage engine parts. Change the oil and filter before winterizing.
- Run the engine: After changing the oil, run the engine briefly to circulate clean oil.
- Inspect for leaks: Check for oil leaks and fix them before storing your boat.
Cooling System: Flush and Safeguard
- Flush the system: Use fresh water to flush out salt, debris, and old coolant from the engine’s cooling system.
- Add antifreeze: Pour marine-grade antifreeze into the system and run the engine until it exits the exhaust. This prevents freezing and corrosion.
- Check hoses & clamps: Inspect hoses for cracks or bulges and replace as needed. Tighten or replace any rusted clamps.
Fuel System: Stabilize and Secure
- Add fuel stabilizer: Pour a fuel stabilizer into the tank and run the engine for 10–15 minutes to distribute it through the system.
- Fill the tank: Keep the tank nearly full to reduce condensation and prevent rust inside.
- Replace fuel filters: Change out old filters to ensure clean fuel delivery in spring.
Electrical System: Disconnect and Preserve
- Remove the battery: Take out the battery, clean the terminals, and store it in a cool, dry place.
- Keep battery charged: Charge the battery periodically throughout the winter to maintain its lifespan.
- Inspect wiring: Look for frayed wires or loose/corroded connections, and repair or replace them as needed.
Bonus Tips
- Log your maintenance: Keep a record of all work performed for easy reference next season.
- Cover your boat: Use a high-quality cover and store your boat in a dry, sheltered area.