The Complete Inboard Engine Winterizing Checklist

Why Winterizing Matters

Improper winterization is the single most expensive mistake a boat owner makes. Cracked engine blocks, corroded fuel systems, and seized through-hulls can turn a routine winter into a $5,000–$15,000 repair bill.

The good news: done correctly, winterization is straightforward.

The Checklist

Engine

Change engine oil and filter while warm

Flush raw water cooling system with fresh water

Run antifreeze through raw water circuit until pink at exhaust

Fog all cylinders and carburetor with fogging oil

Disconnect battery or connect to trickle charger

Fuel System

Fill tank to 95% capacity (prevents condensation)

Add fuel stabilizer — run engine 10 minutes to distribute

Inspect fuel lines for cracks or softness

Hull and Drive

Inspect anodes (zincs) — replace if less than 50% remaining

Lubricate steering cable and helm

Grease propeller shaft

When to Call a Pro

Check Boatee for rated marine mechanics in your area with community pricing — before you call.