Simple 2-Stroke Outboard Winterization
Goal: Protect fuel system, cylinders, and gearcase; prevent corrosion/freezing.
Stabilize fuel
Add marine stabilizer to the tank; run on muffs 10–15 min so treated fuel reaches the carbs/injectors.
Fog the engine
While warm, spray fogging oil into the air intake at elevated idle until it smokes heavily; shut down.
Pull spark plugs, spray 2–3 seconds into each cylinder, crank briefly with the kill switch pulled, reinstall plugs.
Flush & drain cooling
Fresh-water flush 10 min.
Store motor vertical so the leg fully drains (most outboards self-drain).
Lower unit service
Drain and refill gear oil; replace plug gaskets. (Milky oil = water intrusion—note for repair.)
Prop & corrosion check
Pull prop; remove any fishing line; grease shaft.
Battery & exterior
Charge battery, disconnect negative, or remove to warm storage.
Light corrosion-inhibitor spray on powerhead/externals; lube all grease zerks.
Pull bilge/transom drains.
Simple 4-Stroke Outboard Winterization
Goal: Protect fuel system, cylinders, and gearcase; prevent corrosion/freezing.
Stabilize fuel
Add marine stabilizer to the tank; run on muffs 10–15 min so treated fuel reaches the carbs/injectors.
Fog the engine
While warm, spray fogging oil into the air intake at elevated idle until it smokes heavily; shut down.
Pull spark plugs, spray 2–3 seconds into each cylinder, crank briefly with the kill switch pulled, reinstall plugs.
Flush & drain cooling
Fresh-water flush 10 min.
Store motor vertical so the leg fully drains (most outboards self-drain).
Lower unit service
Drain and refill gear oil; replace plug gaskets. (Milky oil = water intrusion—note for repair.)
Prop & corrosion check
Pull prop; remove any fishing line; grease shaft.
Battery & exterior
Charge battery, disconnect negative, or remove to warm storage.
Light corrosion-inhibitor spray on powerhead/externals; lube all grease zerks.
Pull bilge/transom drains.
*Engine oil & filter
Change while warm (gets acids/contaminants out for storage).
*Fuel water-separating filter
Replace canister; prime with stabilized fuel.
*Cylinder protection (EFI-safe)
*Cooling/gearcase/prop/battery
Same as 2-stroke: flush, drain vertical, gear lube service, prop/anodes, battery.