Maintenance
Lawn Mower Winter Storage Checklist: Gas, Battery and Riding Mowers
Most hard-starting spring mowers were not broken in March. They were put away wrong in November. Thirty to sixty minutes of end-of-season care prevents gummed carburetors, rusted decks and dead batteries, and it costs almost nothing. Here is the order to do it in.
Quick answer
- Fuel is the big one. Either add a fuel stabilizer and run it through the system, or run the tank dry, whichever your manual recommends.
- Change the oil while the engine is warm, and clean or replace the air filter.
- Disconnect the spark plug wire (or remove the battery pack/key) before touching the blade or deck.
- Scrape and clean the deck, sharpen or replace the blade, then store dry and covered.
- Store battery packs indoors at the partial charge the manufacturer recommends, not in a freezing shed.
Why winter storage matters so much
Gasoline does not age well. Over a few months in a tank, it can start to oxidize and leave varnish behind, and ethanol-blended fuel can absorb moisture. The tiny passages in a small engine's carburetor are exactly where that residue causes problems. Meanwhile, wet grass packed under the deck holds moisture against steel all winter, and lithium batteries left fully charged or fully drained in the cold can lose capacity.
None of that requires special skill to prevent. It just requires doing the steps before the mower goes into the corner of the garage.
Work outdoors or in a well-ventilated area, with the engine cool when handling fuel. Disconnect the spark plug wire and keep it away from the plug, or remove the safety key and battery on electric models, before you reach near the blade. Wear gloves for blade work. Your owner's manual has the final word on every step below.
Gas push and self-propelled mowers
- Deal with the fuel. There are two common approaches. One is to fill the tank with fresh fuel, add a fuel stabilizer at the label rate, and run the engine for several minutes so treated fuel reaches the carburetor. The other is to run the engine until it stops from lack of fuel. Check your manual: some manufacturers prefer one method over the other, and some mowers have a fuel shutoff valve that makes running dry easier.
- Change the oil. Warm oil drains more completely and carries more contaminants out with it. Use the type and amount listed in the manual, and dispose of used oil at a recycling drop-off.
- Service the air filter. Paper filters are usually replaced; foam filters are often washed, dried and lightly oiled per the manual.
- Check the spark plug. Inspect it for heavy carbon or a worn electrode and replace it if needed. Many people simply replace it yearly because it is inexpensive.
- Clean the deck. With the plug wire off, tip the mower the way the manual specifies (often air filter and carburetor side up to keep oil and fuel where they belong) and scrape off packed clippings. A plastic scraper and a stiff brush work well.
- Sharpen or replace the blade. Doing it now means you start the season with a clean cut. Balance the blade after sharpening.
- Lubricate and inspect. Check wheels, height adjusters and cables. Lubricate points the manual lists.
- Store it clean and dry. Indoors is best. Keep it away from pilot lights and other ignition sources if any fuel remains.
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Riding mowers and lawn tractors
Everything above applies, plus a few items specific to larger machines:
- Battery. Remove it or disconnect it, clean the terminals, and keep it charged with a battery maintainer designed for its type. A lead-acid battery left discharged in freezing temperatures can be damaged.
- Tires. Inflate to the pressure on the sidewall or in the manual. Flat-spotted or soft tires are common after winter.
- Belts and pulleys. Look for cracking, glazing or fraying, and check idler pulleys for wobble or noise.
- Grease fittings. Many decks and front axles have zerk fittings that need a few pumps of grease.
- Deck. Remove the deck or raise it fully and clean the underside. Hydraulic and zero-turn machines may have their own deck-wash ports.
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Battery-powered mowers
Battery mowers skip fuel and oil entirely, which is one of their biggest advantages. Winter care is mostly about the battery and the deck.
- Remove the battery pack and the safety key.
- Clean the deck and vents. Most manufacturers say not to hose down the motor housing; brush or wipe instead.
- Store packs indoors, somewhere cool and dry that stays above freezing. Most manufacturers recommend a partial charge for long storage rather than 100 percent or empty, so check the manual for their recommended level.
- Do not leave packs on the charger all winter unless the manufacturer says the charger is designed for that.
- Check the pack and charger for cracked cases or damaged contacts. Do not use a damaged lithium pack.
If you are shopping for a spare pack, read our notes on buying a used lithium mower battery before buying secondhand.
Fuel choices that make storage easier
Many small-engine manufacturers specify fuel with no more than 10 percent ethanol, and E15 and higher blends are not approved for most small engines. Some owners use ethanol-free gasoline, where available, or canned pre-mixed engine fuel for the last tank of the season. Both reduce varnish and moisture problems, at a higher price per gallon. For a single push mower, that premium for the final tank can be worth it.
| Approach | Pros | Cons |
|---|---|---|
| Stabilizer + run engine | Simple, tank stays wet so seals stay conditioned | Fuel still ages; stabilizer only slows it |
| Run tank dry | Nothing left to go stale in the carburetor | Some fuel may remain in the bowl; check manual |
| Ethanol-free or canned fuel for last tank | Less varnish and moisture risk | Costs more; not available everywhere |
Where and how to store it
A dry garage or shed is fine for the mower itself. Cover it with a breathable cover rather than plastic sheeting that traps condensation. If you have rodents, check under the hood and in the air filter housing in spring; mice like to nest in engine compartments.
Many walk-behind mowers have handles that fold for storage. Some can be stored upright on end, but only if the manual says that model is designed for it, because tipping the wrong way can let oil reach the air filter or cylinder.
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Spring start-up checklist
- Check the oil level and look for leaks under the storage spot.
- Reconnect the spark plug wire or reinstall the battery.
- Fill with fresh fuel if you ran it dry.
- Check tire pressure and the air filter for nests.
- Start it outdoors and let it run a minute before mowing.
If it still will not start, the culprit is usually fuel-related. A carburetor cleaning is often a reasonable DIY job; if it involves more than that, see our post on when an outdoor tool belongs with a professional repair shop.
Frequently asked questions
Should I run my lawn mower out of gas for winter?
It depends on the manufacturer. Some recommend running the tank dry; others recommend stabilized fuel left in the tank. Your owner's manual will say which approach it prefers for that engine.
Can I leave my mower outside under a tarp all winter?
It is better stored indoors. A tarp can trap condensation and lets moisture and rodents in. If outdoor storage is your only option, use a breathable cover and raise the mower off wet ground.
Do I need to change the oil before storing a mower?
Changing it in fall is a good habit because old oil holds acids and contaminants that sit against engine parts all winter. Check your manual for the recommended interval.
How should I store a lawn mower battery over winter?
Store lithium packs indoors in a cool, dry place above freezing, at the partial charge level the manufacturer recommends. For riding mower lead-acid batteries, keep them charged with a suitable maintainer.
The bottom line
Winter storage is not complicated: handle the fuel, change the oil, clean the deck, take care of the blade and battery, and store the mower dry. Do it every fall and most spring "won't start" problems never happen. When in doubt about a specific step, the owner's manual for your engine is the authority.