If you want your mower to start on the first pull next spring, learning how to winterize a lawn mower is one of the highest-value maintenance jobs you can do this fall. Gasoline goes stale in as little as 30 days, and old oil left sitting all winter turns acidic and corrodes internal parts. Skip the winter prep, and you may face a mower that sputters or refuses to start when the grass starts growing again.
The good news is that knowing how to winterize a lawn mower takes less than an hour for most push mowers, and only a little longer for a riding mower. The steps below follow the same basic logic manufacturers recommend: stabilize or remove the fuel, change the oil, protect the engine, clean the deck, and store the machine somewhere dry. Keep your operator’s manual nearby for model-specific details, and work through the steps in order.
Before you start, gather your supplies: fuel stabilizer, fresh engine oil, a new spark plug, an air filter if yours is dirty, a spark plug wrench, an oil drain pan, a stiff brush, and a breathable mower cover. Wear gloves and safety glasses, and let the engine cool completely before you begin. This guide to how to winterize a lawn mower covers each step in the order you will use them.
Table of Contents
1. Run the Last Mow and Empty the Grass Bag
The first step in how to winterize a lawn mower is one final, normal mow. Cut a little shorter than usual, which helps prevent snow mold over winter, then empty the grass bag completely, because wet clippings left inside will rot and smell.
While the engine is still warm from that last mow, you are in the perfect window for the fuel and oil steps that follow. Warm oil drains more completely, but keep your hands away from the muffler and engine block.
2. Stabilize the Fuel or Drain the Tank
Fuel is the number one reason mowers fail to start in spring. The simplest option is to add fuel stabilizer to fresh gasoline, top off the tank, and run the engine for five to ten minutes so the treated fuel circulates through the carburetor. A full tank also leaves less room for condensation inside the tank. Mastering how to winterize a lawn mower starts with fuel, because stale fuel causes most spring failures.
The alternative is to drain the tank completely and run the engine until it stalls, leaving the fuel system dry. You must dispose of drained fuel properly at a hazardous waste facility, never on the ground or down a drain. For most homeowners, the stabilizer route is easier and safer, and it protects the carburetor from the gum and varnish stale ethanol-blended fuel leaves behind. Briggs & Stratton publishes a detailed guide to putting your mower to rest for winter that covers both approaches.
3. Change the Oil While the Engine Is Warm
Old oil contains acids, moisture, and metal particles from a season of mowing, and leaving it in the crankcase all winter lets those contaminants attack bearings and seals. Knowing how to winterize a lawn mower means changing that oil now: with the engine warm, disconnect the spark plug wire, drain the old oil into a pan, and take it to an auto parts store or recycling center, since most accept it free of charge.
Refill with fresh oil of the type and amount your manual specifies, usually SAE 30 or a multi-grade like 10W-30. Check the level with the dipstick and do not overfill, because too much oil can smoke, foul the plug, and damage seals.
4. Replace the Spark Plug and Check the Air Filter
A fresh spark plug is cheap insurance for a first-pull start in spring. Remove the old plug, check the gap against your manual’s specification, and install the new plug snugly without overtightening. A worn plug causes hard starting and rough running.
While you are at it, inspect the air filter. A clogged paper filter should be replaced, while a foam filter can usually be washed, dried completely, and lightly oiled before reinstalling. This is also a good moment to follow the same seasonal rhythm you use elsewhere around the house, like when you winterize outdoor faucets before the first hard freeze.
5. Clean the Deck Thoroughly
Grass clippings caked under the deck trap moisture against bare metal all winter, and that is how rust starts. When you learn how to winterize a lawn mower properly, deck cleaning is never optional. With the spark plug wire disconnected and the mower tipped with the air filter side up, scrape the deck clean with a putty knife or stiff brush, hose it off if needed, and dry it thoroughly afterward.
Once the deck is clean and dry, inspect it for cracks or peeling paint and touch up bare metal with rust-inhibiting spray paint. A clean deck also cuts better next spring, because clippings discharge freely instead of clumping. This is a practical part of how to winterize a lawn mower that also improves next season’s cut.
6. Sharpen or Replace the Blade
A dull blade tears grass instead of cutting it, leaving ragged tips that turn brown and invite disease. Part of how to winterize a lawn mower well is dealing with the blade now, while the mower is already out of service. Remove the blade with the spark plug wire disconnected and the blade blocked, sharpen it with a file or bench grinder at the original angle, and balance it afterward, since an unbalanced blade vibrates and wears out spindle bearings.
If the blade is nicked, cracked, bent, or worn thin, replace it rather than sharpening it. A new blade costs far less than a spindle repair. When you learn how to winterize a lawn mower, checking blade condition is a quick safety step.
7. Remove and Store the Battery (Riding Mowers)
If your riding mower has a battery, removing it is one of the most important steps in how to winterize a lawn mower for cold climates. Cold saps charge, and a battery left connected can drain completely over a few months. Disconnect the negative cable first, then the positive cable.
Clean the terminals with a wire brush, coat them lightly with terminal protector, and store the battery in a cool, dry place away from furnaces and water heaters. Check the charge monthly over winter and top it up with a trickle charger if it drops. This routine is essential when you plan how to winterize a lawn mower with a riding model.
8. Lubricate Moving Parts and Check the Tires
Winter storage is hard on grease points, cables, and tires, so this step of how to winterize a lawn mower is easy to skip and costly to regret. Lubricate the wheel bearings, pivot points, and control cables per your manual, and check the drive belt for cracks or fraying. Replace a worn belt now, when you have time, rather than in spring.
Inflate the tires to the manual’s pressure, and park a riding mower on plywood or cardboard rather than directly on cold concrete, which can flatten tires over months. Rolling it a few inches monthly also helps prevent flat spots. These small details complete how to winterize a lawn mower for the storage season.
9. Cover It and Store It Somewhere Dry
The final step in how to winterize a lawn mower is proper storage. Park the mower in a garage or shed and cover it with a breathable mower cover rather than a plastic tarp, which can trap condensation and cause rust.
Keep the mower away from furnaces, water heaters, and pilot lights if any fuel remains in the tank, and store fuel cans separately in a cool, ventilated area. Write a short note listing what you did, such as the oil type and whether the fuel was stabilized or drained, so spring startup becomes a five-minute job. A written note is a simple habit that makes how to winterize a lawn mower easier to repeat next year.
Winterizing Checklist for Electric and Battery Mowers
Electric mowers need a shorter version of how to winterize a lawn mower, but they still benefit from winter care. Clean the deck, sharpen or inspect the blade, and wipe down the housing. Remove the battery pack, store it indoors at room temperature at roughly a half charge, and never leave it in a freezing garage all winter. Check the charger and cord for damage and store everything together. The same seasonal mindset pays off indoors, where jobs like changing a furnace filter keep the house running efficiently through winter.
Common Winterizing Mistakes to Avoid
The most common mistake is leaving untreated fuel in the tank, the leading cause of spring carburetor problems. The second is skipping the oil change, which lets acidic oil sit in the engine for months. A third is storing the mower uncovered outdoors, where rain, snow, and freeze-thaw cycles attack every surface. Never store a mower with untreated fuel next to a pilot light or furnace. Small mistakes in November, when you first learn how to winterize a lawn mower, become expensive repairs in April.
FAQ
How long does it take to winterize a lawn mower?
For most push mowers, the full job takes 45 to 60 minutes, including the oil change and deck cleaning. Riding mowers take about 90 minutes. Doing it in one session beats spreading it across weekends and forgetting a step. That timing assumes you follow how to winterize a lawn mower step by step, without rushing the fuel and oil work.
Should I run the tank empty or use fuel stabilizer?
Both methods work when done correctly. Fuel stabilizer is easier: treat fresh fuel, top off the tank, and run the engine for a few minutes. Draining the tank also works, but you must dispose of the old fuel properly and run the engine until it stalls. Pick one method and do it completely.
Do I need to winterize an electric lawn mower?
Yes, though the job is simpler. Electric mowers have no fuel or oil to worry about, but they still need a clean deck, a sharp blade, and proper battery storage indoors at room temperature.
When is the best time to winterize a lawn mower?
When you plan how to winterize a lawn mower, do it right after the last mow of the season, usually in late October or November, and before the first hard freeze. If you have already had a freeze, you can still winterize, just work in a garage.
Will my mower start in spring if I skip winterizing?
It might, but the odds are against you. Stale fuel clogs carburetors, old oil corrodes parts, and a dead battery will not turn the engine over. Winterizing takes under an hour, while a carburetor cleaning can cost many times more and delay your first mow by weeks.
Final Thoughts
Learning how to winterize a lawn mower is a small fall investment that pays off with a reliable first start in spring, a longer engine life, and fewer repair bills. Pair it with other fall jobs like cleaning gutters so the whole property is ready for cold weather. Work through the nine steps once, keep the supplies in one spot, and the job gets faster every year. When spring arrives, reinstall the battery if you removed one, check the oil level, add fresh fuel if you drained the tank, and pull the cord.