Complete Outboard Motor Winterization Guide: Protect Your Investment

Proper winterization is essential for protecting your outboard motor during the off-season. Skip these steps, and you risk freeze damage, corrosion, and frustrating startup problems come spring.

Why Winterization Matters

Water left in the cooling system can freeze, cracking the engine block or water pump housing. Old fuel degrades, clogging carburetors and injectors. Moisture causes internal corrosion. A few hours of preparation prevents thousands in repairs.

Step 1: Run the Engine and Add Fuel Stabilizer

1. Fill the fuel tank to 90% capacity (prevents condensation)
2. Add marine fuel stabilizer per manufacturer directions
3. Run the engine for 10-15 minutes to circulate treated fuel
4. This ensures stabilized fuel reaches the entire fuel system

Step 2: Change the Engine Oil (Four-Strokes)

1. Run engine until warm (helps oil drain completely)
2. Remove drain plug and drain old oil
3. Replace oil filter
4. Refill with manufacturer-recommended oil
5. Old oil contains acids that corrode bearings during storage

Step 3: Flush the Cooling System

1. Connect flush muffs or use a flush bag
2. Run fresh water through the engine for 10+ minutes
3. This removes salt, sand, and debris from cooling passages
4. Essential for both saltwater AND freshwater boats

Step 4: Fog the Engine

1. Remove the air intake cover/flame arrestor
2. Start the engine on muffs
3. Spray fogging oil into carb throats or throttle body while running
4. Continue until engine stalls from excess oil
5. This coats internal components with protective oil film

Step 5: Change Lower Unit Gear Oil

1. Remove both drain and vent plugs
2. Drain completely (check for water or metal particles)
3. Refill from bottom until oil flows from top hole
4. Replace both plugs with new gaskets

Step 6: Protect External Components

• Spray all electrical connections with corrosion inhibitor
• Apply marine grease to all zerk fittings
• Touch up any paint chips to prevent rust
• Apply light oil to tilt/trim rams

Step 7: Battery Care

• Remove batteries and store in cool, dry place
• Keep on trickle charger or charge monthly
• Clean terminals and apply dielectric grease

Need Winterization Supplies?

We stock fogging oil, fuel stabilizer, gear oil, and all winterization essentials. Contact us for product recommendations specific to your engine.