| Key Takeaways |
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| • To winterize your lawn mower, manage the fuel, change the oil, clean the deck, service the spark plug and air filter, and store it somewhere dry. • Fuel is the biggest risk: Either drain the tank completely or fill it with stabilized fuel. Untreated gas can start gumming up the fuel system in about a month. • Electric and battery mowers still need winterizing, but you skip the fuel, oil, spark plug, and air filter steps and focus on the battery and storage. |
Winter is coming, and your mower deserves some care before it hibernates. Proper lawn mower winterization involves a handful of steps, including removing or stabilizing fuel, sharpening blades, and servicing the spark plug, oil, and air filter.
This guide walks you through all 10 steps in order, explains why each one matters, and covers how the process changes for electric mowers. Do it once each fall, and your mower should start easily and last longer.
If you would rather skip the wrench work, you can hand the mowing and the upkeep that comes with it to LawnStarter’s local mowing pros.
| Project difficulty: Intermediate Estimated time to complete: 1 hour for electric mowers; 2 to 4 hours for gas-powered mowers Project cost: Electric mowers have minimal winterization costs related to the engine; gas-powered mowers typically cost around $30 to $40 to DIY. For all mowers, the cost to sharpen or replace the blades ranges from $5 to $40. Expect to pay $100 to $200 for professional winterization, depending on the type of mower. |
Do You Need to Winterize Your Lawn Mower?
Yes, winterizing your lawn mower is a non-negotiable, especially if you own a gas mower.
A little end-of-season care pays off with an easy spring start and a mower that lasts longer. Electric and battery mowers need attention too, but the checklist is shorter. You can skip the fuel, oil, spark plug, and air filter steps, cutting your winterization tasks by about half.
How to Winterize Your Lawn Mower Step by Step
Set aside an afternoon and work through these 10 steps in order. The first few double as safety measures, so complete them before the rest.
1. Take Out the Battery
If you have an electric mower, or your gas-powered mower has an electric start, begin by removing the battery. First disconnect the negative (black) terminal, followed by the positive (red).
Battery preparation varies slightly depending on the type:
Remove any corrosion from lead-acid terminals using a wire brush and a baking soda and water solution.
Check the electrolyte levels on non-sealed batteries (common on riding mowers), and top off with distilled water if necessary.
Then store the battery in a cool, dry place, ideally somewhere it will not freeze. A lead-acid battery slowly loses charge in storage, so a battery tender or trickle charger is a handy way to keep it topped off over the winter. For lithium-ion batteries, store them at a charge level between 50% and 80%.
2. Replace the Spark Plug
Disconnect the spark plug wire, and remove the old spark plug using a special spark plug socket (which is longer) or a spark plug wrench tool.
Check the gap on the new plug, and use a gapping tool so it matches your manual’s specifications.
Hand-tighten the new plug, and then give it another quarter-turn with the wrench. Don’t overtighten it or you’ll strip the threads.
Do not reconnect the spark plug wire until spring.
3. Remove or Stabilize the Fuel
Over time, fuel degrades, and the gummy residue can clog fuel lines and filters, causing big problems. Most pump gas today contains ethanol blends, which can be tougher on the rubber and gaskets in older mower engines.
One of the most important winterizing steps is to drain the mower’s fuel completely or add stabilizer to the gas tank.
You can drain the fuel a few different ways: using a siphon pump, tipping the mower, or disconnecting the fuel line. If using a stabilizer, add the recommended amount to a full tank and then run the mower for 10 minutes. Do not put this step off, because untreated gas can begin to degrade in as little as 30 days.
It is advice the pros live by. As Chelsea Morris, owner of High-Class Grass in Virginia Beach, Virginia, says, “Make sure you keep good fuel in the mower.”
| Drain the Fuel | Add Stabilizer |
| Best for long storage or when you cannot run treated fuel through the engine. Removes the gas that gums up carburetors. | Best when you want the mower ready to run. Keeps a full tank from degrading and blocks moisture and rust. |
4. Clean Your Mower Thoroughly
Cleaning your mower makes it easier to winterize, plus storing it clean helps prevent rust and corrosion.
I like to start with the toughest job first, which is cleaning the underside of the deck. Prop one side of the mower up (I put chunks of wood under it), and remove the blades. Use a plastic scraper or putty knife to remove as much of the buildup as you can.
My Tip: If the bottom of the deck is really bad, soak the grass with the hose, and then try to scrape it off.
Then hose everything down, keeping water away from the engine, air filter, and electrical components. Use a soft scrub brush to remove caked-on dirt. Let everything dry, and then coat it with a thin layer of WD-40.
5. Sharpen the Blades
Since you removed the blades to clean under the deck, inspect them for nicks, cracks, or excessive wear. If they are good for another year of use, sharpen them and reinstall. If they are not in good condition, buy a new pair to put on the mower.
See Related: How Often Should You Sharpen Lawn Mower Blades?
6. Change the Engine Oil
Changing your mower’s oil is an essential maintenance task, especially before winter storage. Morris recommends checking and changing it twice as often as the manufacturer recommends, a habit she learned from her father.
“Even with your vehicle, if you change your oil just as it’s recommended, that’ll put half the mechanic shops out of business,” she says.
My Tip: Run the mower for a few minutes to warm the oil and make it easier to drain.
Place an oil pan underneath or next to the mower, and then remove the drain plug or tip the mower (with the spark plug and gas cap side up) to empty the oil.
Replace the oil filter if your mower has one, and fill the mower with the correct type of oil. Your manual should tell you what to use. Most mowers use a thinner oil, typically SAE 30 or 10W-30.
Note: Avoid using car oil in your mower, and use a small engine oil designed for lawn mower engines instead. Car oil is formulated for the high temperatures and vibration of automotive motors. It will work in a pinch, but you risk engine damage and voiding your warranty.
7. Service the Air Filter
Remove the air filter (only on gas-powered mowers) and inspect it carefully. A dirty, clogged filter restricts airflow, making your mower work harder.
Paper filters should be replaced if they are dirty or damaged. Never try to clean them with water.
Foam filters can be washed in warm, soapy water, squeezed dry, and then lightly oiled with engine oil.
8. Check Belts and Cables
Give everything a once-over, making sure the belts on riding mowers and any cables (throttle, choke, pull-start) are not frayed or worn. Replace anything that shows excessive wear.
9. Lubricate Moving Parts
Lubrication keeps the mower’s moving parts operating smoothly, preventing seized parts that can be costly to repair.
Apply a thin coating of a light machine oil or spray lubricant like WD-40 to cables, pivot points, and other moving components. Pay special attention to wheel bearings and height adjustment mechanisms. Do not forget the choke and throttle linkages on gas mowers.
Pump grease fittings (if your mower has them) with fresh grease until it expels the old grease.
After everything is lubricated, wipe off excess lubricant to prevent dirt accumulation.
10. Prepare for Storage
The best storage location is a clean, level spot that is away from moisture and protected from temperature extremes. It should be well-ventilated and away from heat sources.
If your mower handle folds down and you need to conserve space, fold it down.
Place cardboard under inflatable tires to prevent flat spots.
Cover your mower with a breathable tarp or a specially designed mower cover.
If you have no choice but to store it in a damp area, purchase some moisture absorbers to place around it.
FAQs
Start winterizing just after you are done mowing for the season, which is typically late fall, just before the first hard frost for your area. Do not wait until it is freezing cold and uncomfortable to work outside, even in your garage or shed.
Reconnect the spark plug wire and battery, check the oil level, and make sure the fuel is fresh, adding new gas if the tank sat untreated. If you prepped the mower following the steps above, it should fire right up in spring.
A high-quality fuel stabilizer claims it can keep gas fresh for up to 24 months, but by about the one-year mark, even stabilized fuel will start to degrade.
Fuel stabilizer prevents stored gas from degrading and becoming gummy. Octane booster improves a fuel’s resistance to detonation in high-performance engines, minimizing knocking and preventing engine damage from low-octane fuel.
Turn to the Pros for Help
As sure as winter comes each year, you will need to prep your lawn mower for storage. Do not just leave it parked outside after the final cut of the year. Take an afternoon or two to winterize it so it will work better come spring and last longer.
If mechanical work is not your forte, contact a local LawnStarter mowing pro to take care of the mowing (and the resulting lawn mower maintenance) instead.
Main Image: Winterize your lawn mower and change the spark plugs. Image Credit: Derek Lacey / LawnStarter
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