How to Winterize a Mercury Boat Engine

It is recommended that you perform routine maintenance on your boat engine every 100 miles, or once per year, whichever comes first. Winterizing your boat is routine maintenance that must be performed, once a year, for anyone who lives in a climate that doesn't allow winter boating. If there is a chance that the temperature drops below freezing, winterize your boat.

Things You'll Need

• Antifreeze
• Fuel stabilizer
• Wire
• Outboard oil
• Water-separating fuel filter
• Four-stroke oil
• Oil filter
• Drive gear lubricant
• Silicone spray

Instructions

1. Open the petcock valves to ensure that any remaining water gets drained. Clean the valves with a piece of wire, freeing any blockages or debris.

2. Remove one end of the water hoses that feed the engine block and the exhaust manifold.

3. Pour antifreeze into the hoses until it runs out the petcocks.

4. Pour a small amount of outboard oil into the water-separating fuel filter to fog your engine. Turn on the engine so that it can run and ingest the oil you just poured.

5. Change the water-separating fuel filter (if you have one).

6. Change the oil in the engine and replace the filter.

7. Add fuel stabilizer to the gas tank, and run the engine so that it mixes well with any remaining fuel in the system. This allows treated fuel to make its way throughout the fuel system, and not just sit in the gas tank.

8. Change the drive gear lubricant.

9. Coat the electrical system with a fine mist of silicone spray. This keeps it from corroding during the winter, and shorting out when you go to use the electrical systems come spring.

Tips & Warnings

• If you are unsure about any part of this, it's best to let the professionals at the marina handle it. Any money you save by doing it yourself can quickly be lost by doing it incorrectly.

References

• Mercury Marine: Service and Warranty
• Lake Conroe Marine: Winterize Your Mercury Engine
• Mercury Marine Blog: Winterizing Your Engine