How to Winterize a Lawn Mower: Gas, Riding and Battery
To winterize a lawn mower, deal with the fuel first, then change the oil, clean the deck, check the blade and spark plug, and store it somewhere dry. For a gas mower, follow your engine maker on the fuel: Briggs & Stratton says store it with a full tank of stabilized gas, and Honda says run it dry if it will sit more than 3 months.
Battery mower? Skip the fuel and oil. Pull the battery, bring it inside, and store it part charged. The steps below cover gas push mowers, riding mowers and battery mowers.
Gas push mower: stabilize the fuel or run it dry (your manual decides), change the oil while it's warm, clean the deck with the spark plug wire off, sharpen the blade, and store it in a dry spot away from any furnace, water heater or dryer. Riding mower: same, plus run the stabilized fuel about 10 minutes outdoors (never in a garage, even with the door open), then pull the battery and keep it cool and dry. Battery mower: take the pack inside, below 80°F, at 30 to 50% charge (EGO's manual), and fully charge it every six months.
First call: stabilize the gas or run it dry?
Engine makers split on this one. Read your manual. Illinois Extension gives both choices for 4-cycle mowers: run it dry, or stabilize a full tank of fresh gas. It also names stale fuel and gummed-up carburetors as the most common reason engines won't start in spring. Here's what two engine makers say.
| Engine maker | What they say for winter | Why |
|---|---|---|
| Briggs & Stratton | Fill the tank with fresh gas plus stabilizer. Run the engine a few minutes so treated gas reaches the carburetor. Store it full. | A full tank leaves less room for moisture. Untreated gas starts to break down in as little as 30 days. |
| Honda (HRN216 manual) | Next use 1 to 3 months away: fill the tank, add stabilizer, run 10 minutes, then shut the fuel valve and run the carburetor dry. Next use more than 3 months away: run the whole fuel system empty. | Stabilizer has a shelf life. Honda says not to leave gas in the mower more than 3 months unused. |
Mower parked from November to March? That's more than 3 months. On a Honda, run it dry. On a Briggs, stabilize and fill. Other engine? The manual has a storage page. Follow it.
Running it dry: do it outdoors. Past 3 months, mow until the tank is low, then leave the fuel valve open and run it until it quits. That empties the tank and the carburetor (Honda HRN216 manual). Shutting the valve and running about 3 minutes empties only the carburetor. That's Honda's step for a 1 to 3 month layup.
Fuel stabilizer dose
Go by the bottle. For STA-BIL Storage, the maker gives 1 ounce per 2½ gallons of gas, and that covers 2-stroke mix too. Then run the engine outdoors for 5 minutes so treated gas fills the whole fuel system. The maker says it keeps gas fresh up to 24 months, depending on the gas and how it's stored.
| Gas treated | STA-BIL Storage (1 oz per 2½ gal) |
|---|---|
| 1 gallon | About 0.4 oz (2½ teaspoons) |
| 2½ gallons | 1 oz |
| 5 gallons | 2 oz |
Treat the gas can, not just the mower. Shop math: a push mower tank holds well under a gallon, so the can is where most of the gas sits all winter. Honda's HRN216 tank holds 0.24 gallon.
Stabilizer keeps fresh gas fresh. It won't fix old gas. Honda says it "will not reconstitute stale fuel." Gas from August? Use it up, or take it to your county's household hazardous waste drop-off. Then stabilize fresh gas. Honda says don't use gas with more than 10% ethanol. Briggs says the same: up to 10% ethanol, and never 15 to 85% ethanol blends.
How to winterize a gas push mower
Order matters. Treated gas has to reach the carburetor before you shut the engine down for good, and the cylinder oil goes in last, after the final run. Pick the path your engine maker gives.
Path A: stabilize and fill (Briggs & Stratton style)
- Treat the gas can. Add stabilizer to fresh gas in the can at the bottle's dose.
- Fill the tank and run it, outdoors. Run the engine 5 to 10 minutes so treated gas fills the carburetor. Never in a garage or shed, even with the door open.
- Stop the engine and pull the spark plug wire. Every time before work near the blade.
- Change the oil while it's warm. Warm oil drains faster. With a full tank, use a siphon pump or the drain plug rather than tipping the mower, because a tipped full tank can leak gas. Refill with the oil type and amount in your manual. Take the used oil to a recycling center or service station. Never the trash, the ground or a drain.
- Let it cool, then clean underneath. Wear heavy gloves. Scrape off packed clippings. Tip it only the way your manual says.
- Sharpen or replace the blade. See how to sharpen lawn mower blades.
- Clean or replace the air filter. Per the manual.
- Top off the tank once the engine is cool, with more treated gas from the can, so it stores full (Briggs).
- Store it dry. See the storage step below.
Path B: run it dry (Honda style, more than 3 months)
- Run the tank empty, outdoors. Mow until the tank is low, then leave the fuel valve open and run it until it quits. Never in a garage or shed.
- Pull the spark plug wire.
- Change the oil while it's warm. Honda drains by tipping: right side down, fuel cap side up, fuel valve off. Honda gives every 6 months or 50 hours anyway. Recycle the used oil.
- Let it cool, then scrape the deck, sharpen or replace the blade, and clean the air filter.
- Oil the cylinder (Honda's step), last. Pull the spark plug. Pour in 1 teaspoon (5 cc) of clean engine oil. Pull the starter rope a few times. Reinstall the plug. Then pull the rope slowly until you feel resistance. That closes the valves so moisture stays out. Don't start the engine again after this.
- Store it dry.
Storage, both paths: garage or shed, wheels level, somewhere dry. Cover it once it's cool if it sits in dust, but not with sheet plastic (Honda: it traps moisture). With gas inside, Honda says keep it away from a furnace, water heater, clothes dryer, or a spot where power tools run. Fuel valve off.
How to winterize a riding mower
Same jobs, bigger engine, plus a battery. Briggs & Stratton's tractor steps:
- Stabilize and top off. Mix stabilizer into a can of fresh gas and top off the tank. Run the engine about 10 minutes outdoors. Never in a garage or shed, even with the door open.
- Change the oil and oil filter while the engine is warm. Oil the new filter gasket lightly. Tighten a half turn after it seats.
- Change the fuel filter once the engine and muffler are cool. Rag under the line. Nothing nearby that can ignite.
- Replace the spark plug. Gap it to the spec in your manual.
- Pull the battery. Negative cable first, then positive. Clean the terminals. Store it in a cool, dry place like the garage, shed or basement. Briggs's push-mower steps add: away from gas cans, water heaters and furnaces.
- Key out. Spark plug wire off. Then clean the deck and engine, and cover the tractor.
Briggs doesn't give a charging schedule for the battery in these steps. Check your tractor manual or the battery maker for that. Mowing tips for spring are in the riding mower guide.
How to winterize a battery mower
No gas. No oil. The battery is the whole job. Remove the safety key first. EGO's 56V battery manual, for storage longer than 30 days:
- Store the pack below 80°F and dry. EGO gives 50 to 80°F as the best storage range.
- Store it at 30 to 50% charge. After a month in storage, the pack drops itself to about 30% and holds there, so there's no need to run it down.
- Fully charge it every six months in storage, and again before first use in spring.
- For best results, charge it between 41 and 104°F.
- Don't store it outside or in a vehicle.
So a pack left in an unheated garage that drops below freezing sits well under EGO's 50°F optimum. Bring it inside. A closet works. Then brush the clippings off the deck, check the blade, and store the mower dry. Other brands have their own numbers. Read your battery manual. Shopping for one? See the best battery lawn mowers for 2026.
Spring start-up
- Oiled the cylinder? Honda says it may smoke for a moment at first start. Normal.
- Ran it dry? Fill with fresh gas.
- Battery mower? Fully charge the pack first.
- Riding mower? Reinstall the battery. Positive cable first, then negative, the reverse of removal.
- First cut of the year? Set the deck with the mowing height calculator for your grass.
Won't start in spring? Work through how to repair a lawn mower. Have a sprinkler system too? It needs its own winterizing before the first hard freeze.
Your mower's manual wins over this guide where they differ.
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Handle the fuel first, outdoors: either stabilize the gas, fill the tank and run the engine 5 to 10 minutes, or run it dry, as your engine manual says. Then pull the spark plug wire, change the oil while the engine is warm, let it cool, clean the deck, sharpen or replace the blade, clean the air filter, and store the mower somewhere dry and away from flames. For a battery mower, remove the battery and store it indoors.
It depends on the engine maker. Briggs & Stratton says to store the mower with a full tank of stabilized gas. Honda says not to leave gas in the mower for more than 3 months unused and to run the fuel system empty for long storage. Follow your owner's manual.
Follow the bottle. STA-BIL Storage gives 1 ounce per 2.5 gallons of gas, which is about 0.4 ounce per gallon. Treat the gas can, then run the mower outdoors (never in a garage) for 5 to 10 minutes so treated gas reaches the carburetor.
Take the battery out and store it indoors and dry. EGO's manual says to store it below 80°F at 30 to 50% charge, fully charge it every six months, charge it between 41 and 104°F for best results, and never store it outside or in a vehicle. Check your own battery manual for other brands.
The steps are the same as a push mower plus the battery. Briggs & Stratton says to run stabilized fuel about 10 minutes in a well-ventilated area (outdoors, never in a garage even with the door open), change the oil and oil filter while warm, replace the fuel filter (wait for the engine to cool first), replace the spark plug, and remove the battery (negative cable first) to store it cool and dry.
Sources (5)
- Briggs & Stratton, How to Properly Winterize Your Mower and Garden Tractor & Riding Lawn Mower Storage, and How to Choose Fuel for Your Mower.
- Honda Power Equipment, HRN216VKA/VKPA lawn mower owner's manual (Storage, and Avoiding Fuel-Related Problems).
- Illinois Extension, Yard Equipment Maintenance Tips (Richard Hentschel, 2018).
- Gold Eagle, STA-BIL Storage Fuel Stabilizer product directions.
- EGO Power+, 56V battery operator's manual (storage and charging).
Photos: Joshua Doubek / Wikimedia Commons. Cropped for display · CC BY-SA 3.0
