Winterizing your outboard motor is essential to protect it from freeze damage and corrosion during the off-season. By following a few crucial steps, you can ensure your motor stays in top shape, ready for the next boating season. Here’s a breakdown of how to winterize an outboard motor effectively.

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

Drain the lower unit gear oil by removing the stainless steel plugs at the top and bottom of the gear housing. Inspect the old oil for water contamination (a milky appearance). Refill the unit with fresh oil from the bottom up using a gear oil pump to prevent air pockets.

3. Fuel Stabilization

Add a fuel stabilizer, such as Star Brite's Stabil or Biobor EB, to the fuel tank to prevent gum and varnish buildup. Run the engine for 5-10 minutes to circulate the stabilized fuel through the system.

4. Fog the Cylinders

Fogging the engine prevents rust formation in the cylinders. For carbureted motors, spray fogging oil into the carburetors while the engine runs until it stalls. For EFI (Electronic Fuel Injection) motors, fogging oil should be run through the fuel system instead.

5. Flush with Antifreeze

For optimal protection, flush the cooling system with non-toxic propylene glycol antifreeze. This ensures that any remaining water doesn’t freeze and damage internal components.

6. Apply Corrosion Inhibitors and Final Maintenance

Spray a corrosion inhibitor on the engine’s powerhead. Grease key components such as the pivot and tilt tubes, and remove the propeller to inspect for damage and fishing line tangles. Lubricate the prop shaft and reinstall the prop, or leave it off for theft prevention.

Final Thoughts:

By completing these winterization steps, your outboard motor will be well-protected and ready for storage during the colder months.