How to Winterize a Lawn Mower
In This Guide
Spending forty five minutes in the fall is the difference between a mower that fires on the first pull in spring and one that sits dead with a gummed carburetor. Knowing how to winterize a lawn mower comes down to a short checklist: fuel, oil, spark plug, blade, and a dry place to store it. Below we walk through each step in order so your mower is protected all winter and ready the moment the grass starts growing again.
Step 1: Handle the Fuel
This is the single most important step. Old ethanol fuel breaks down over winter into a varnish that clogs the carburetor, which is why so many mowers will not start in spring. You have two good options.
Stabilize it. Add fuel stabilizer to a full tank and run the engine for five minutes so treated fuel reaches the carburetor. A full tank limits the condensation that causes rust.
Or drain it. Run the mower until it stalls from lack of fuel, then drain the carburetor bowl so no fuel is left to gum up.
Step 2: Change the Oil
Used oil holds acids and moisture that slowly corrode the engine while it sits all winter. Draining the old oil and refilling with fresh oil before storage protects the internals during the months of inactivity.
Warm the engine first so the oil drains cleanly, then refill to the full mark with the grade your manual recommends, usually SAE 30 or 10W-30. This is the perfect time to do it since the engine is coming out of service anyway.
Step 3: Service the Spark Plug
1. Disconnect and remove
Pull the spark plug wire, then unscrew the spark plug.
2. Inspect it
A plug that is black, worn, or fouled is due for replacement, which is cheap and easy.
3. Fog the cylinder
Optionally add a small spoon of clean engine oil into the cylinder and pull the cord slowly a few times to coat it against rust, then refit the plug.
Step 4: Clean the Deck and Sharpen the Blade
Grass packed under the deck traps moisture and causes rust over a long winter. Disconnect the spark plug wire, tip the mower air filter side up, and scrape the underside clean.
Winter is also the ideal time to sharpen or replace the blade while the mower is already tipped and the plug wire is off, so it is ready to cut cleanly in spring.
Step 5: Battery and Storage
On a riding mower, remove or disconnect the battery and keep it on a trickle charger in a cool dry place so it does not drain or freeze. Then store the mower somewhere dry, ideally a garage or shed, away from any furnace or water heater.
A Quick Winterize Checklist
| Step | Why it matters |
|---|---|
| Stabilize or drain fuel | Prevents a gummed carburetor, the top no start cause |
| Change the oil | Removes acids and moisture that corrode the engine |
| Service the spark plug | Ensures an easy spring start |
| Clean deck, sharpen blade | Stops rust and readies a clean cut |
| Battery and dry storage | Protects the battery and prevents rust |
If your mower was put away without winterizing last year and now will not start, that is almost always a gummed carburetor. Wildwood can clean the fuel system at your home and have it running again quickly.
Rather Have a Real Technician Handle It?
A Wildwood technician comes to your driveway, diagnoses the problem, and fixes it on the spot, usually in about an hour. More than 10,000 repairs completed since 2019, with flat rates quoted before we arrive so there are no surprises.