Winterizing Your Outboard: The Complete 7-Step Checklist

Winter is coming. Skip winterization and you're looking at cracked blocks, corroded internals, and an expensive spring. Follow this checklist.

Step 1: Flush the cooling system with fresh water for 10-15 minutes

The 7-Step Winterization Checklist

1. Flush the Cooling System

• Run engine on flush muffs or in a barrel with fresh water for 10-15 minutes
• Removes salt, sand, and debris from cooling passages

2. Stabilize the Fuel

• Add fuel stabilizer to a full tank
• Run engine 10 minutes to circulate treated fuel through the entire system
• Old fuel gums up carburetors and injectors

3. Fog the Engine

• Spray fogging oil into carburetors/throttle bodies while engine runs
• Coats cylinder walls and pistons - prevents corrosion during storage

4. Change Lower Unit Oil

• Drain and replace gear lube
• Milky oil = water intrusion = seal issue - fix before storage

5. Grease All Fittings

• Hit every zerk fitting: steering, tilt/trim, prop shaft, throttle/shift cables

6. Remove the Battery

• Store indoors on a trickle charger
• Cold kills batteries

7. Cover or Store Indoors

• Engine stays on boat? Use a quality engine cover
• Can remove it? Store upright in a dry, climate-controlled space

Proper storage protects your investment through the off-season

Pro tip: Before you winterize, snap a photo of your engine and use our AI Scanner to document the exact make, model, and specs for your records.

Related: Used outboard buyer's checklist · Source: BoatUS Winterization Guide