Quick Answer
Winterizing your lawn mower means draining or stabilizing the fuel, changing the oil, cleaning the deck, and storing it properly before the season ends. Doing this takes about 30–60 minutes and can prevent costly engine damage caused by stale fuel and moisture. Skipping this step is one of the most common reasons mowers fail to start in spring.
Key Takeaways
- Always run the engine dry or add fuel stabilizer before long-term storage
- Change the oil before storing — old oil contains acids that corrode engine parts
- Clean the mower deck thoroughly to prevent rust and mold buildup
- Sharpen or replace the blade each season for a cleaner cut next year
- Store your mower in a dry, covered space away from freezing temperatures
Introduction
As temperatures drop and grass stops growing, your lawn mower deserves more than just being pushed into the corner of the garage. Proper winterization protects your investment, extends engine life, and means you won't be scrambling for repairs when spring arrives[1]. Whether you have a gas push mower, a riding mower, or a battery-powered model, the process is straightforward and well worth the effort.
What Happens If You Skip Winterizing Your Mower?
Leaving untreated gasoline in the tank over winter is the single biggest mistake homeowners make[2]. Modern gasoline contains ethanol, which attracts moisture and begins to break down in as little as 30 days. This leaves behind sticky varnish deposits that clog carburetors and fuel lines — the number one cause of spring start-up failures[3].
Old engine oil is equally damaging. Over a season, oil collects combustion byproducts and becomes acidic. Leaving that oil in the crankcase all winter allows those acids to slowly corrode internal metal surfaces[4]. A simple oil change before storage eliminates this risk entirely.
How Do You Winterize a Lawn Mower Step by Step?
This is the core process for gas-powered mowers. Battery mowers have fewer steps — skip to the battery tip at the end.
Step 1: Drain or stabilize the fuel Run the engine until the tank and carburetor are empty, or add a fuel stabilizer to a full tank and run the engine for 2–3 minutes to circulate it through the system[2]. Stabilizer is the easier option for riding mowers with large tanks.
Step 2: Change the engine oil Drain the old oil while the engine is still slightly warm (it flows out more completely). Refill with the manufacturer's recommended oil grade. This is also a good time to check for oil leaks[4].
Step 3: Remove and inspect the spark plug Pull the spark plug and look for heavy carbon buildup or a cracked insulator. Replace it if in doubt — spark plugs are inexpensive and affect starting reliability significantly[1]. Add a few drops of engine oil into the cylinder before reinstalling to lubricate the piston over winter.
Step 4: Clean the mower deck Disconnect the spark plug wire for safety, then scrape compacted grass clippings from the underside of the deck with a plastic scraper. Rinse with water and let it dry fully. Grass holds moisture and accelerates rust[3].
Step 5: Sharpen or replace the blade A dull blade tears grass instead of cutting it, making your lawn more susceptible to disease. Doing this in fall means you're ready to go in spring[5].
Step 6: Check and clean the air filter Foam filters can be washed with mild soap and water; paper filters should be replaced if visibly dirty or damaged.
Step 7: Store it properly Store your mower in a dry garage or shed. If storing a riding mower, remove the battery and keep it on a trickle charger in a warmer space. For battery-powered mowers, store lithium-ion batteries at around 50% charge in a temperature-stable environment — never in a freezing shed[5].
When Is the Right Time to Winterize Your Mower?
The ideal window is after your final mow of the season, typically when nighttime temperatures consistently drop below 50°F and grass growth slows to a stop[1]. In most northern states, this falls between October and November. In the South and transition zones, it may be December or later[4].
Don't wait until the first freeze — cold temperatures can thicken old oil and make draining it much harder. Aim to complete winterization while the weather is still mild enough to work comfortably.
Conclusion: Set Yourself Up for a Great Spring Start
Winterizing your lawn mower is a one-time, 30–60 minute investment that pays off every spring. Follow these steps before putting your mower away:
- Drain or stabilize fuel
- Change the engine oil
- Inspect and replace the spark plug
- Clean the deck and blade
- Store in a dry, covered location
If you handle these tasks now, you'll avoid the frustration of a mower that won't start just when you need it most. Check your owner's manual for any model-specific recommendations, and your mower will reward you with years of reliable service.