During the off-season, winterizing your outboard motor is crucial to protect it from corrosion and damage from freezing temperatures. Ensuring your outboard motor is in good condition for the next boating season only requires some basic steps. How to properly winterize an outboard motor is described below.

How to Winterize Boat Motors: A Step-by-Step Guide for Outboards

Winter’s coming, and if you want to avoid costly repairs and keep your outboard running smooth next season, it’s time to winterize boat engines the right way. In this guide, we’ll walk you through the steps to protect your outboard motor from freezing temps, corrosion, and long-term damage.

1. Drain and Replace Engine Oil (For 4-Stroke Motors)

Start by warming up the engine using a set of flushing muffs attached to a garden hose, which helps loosen the oil. Drain the crankcase oil and replace it with fresh oil, following the manufacturer’s specifications. Be sure to change the oil filter and use the appropriate API-rated oil.

2. Change Lower Unit Gear Oil

To drain the lower unit, remove the stainless steel plugs on the top and bottom of the gear housing. Check the old oil for any water contamination, such as a milky appearance. In order to prevent air pockets, use a gear oil pump to refill the unit with fresh oil from the bottom up.

3. Fuel Stabilization

To avoid the buildup of gum and varnish, use a fuel stabilizer like Star Brite's Stabil or Biobor EB and add it to the fuel tank. Let the engine run for 5 to 10 minutes, which allows the fuel system to circulate the stabilized fuel.

4. Fog the Cylinders

Fogging the engine avoids rusting in the cylinders. For carbureted motors, pour fogging oil into the carburetors while the engine runs until it stops. Fogging oil should be used in the fuel system in EFI (Electronic Fuel Injection) motors.

5. Flush with Antifreeze

Use non-toxic propylene glycol antifreeze to cleanse the cooling system for the best protection. This prevents any leftover water from freezing and damaging internal parts.

6. Apply Corrosion Inhibitors and Final Maintenance

Spray corrosion inhibitor onto the engine's powerhead. Grease essential parts, including the pivot and tilt tubes, then remove the propeller to check for damage and fishing line tangles. Lubricate the prop shaft, then reinstall the prop, or leave it off to avoid theft.

Final Thoughts:

By following these winterization steps, your outboard motor will be secure, protected from the elements, and ready for storage throughout the cooler months. Don’t forget to add an outboard motor cover or boat cover for an extra layer of defense against dust, moisture, and winter weather.