How to Winterize a Lawn Mower: Gas, Battery and Riding Mower Steps

Come April, the mower coughs twice and quits, and the cause went into the tank last fall. University of Illinois Extension calls stale fuel and gummed-up carburetors the most common reason gas yard tools won't start in spring. After the last mow of the year, run a push mower dry or treat the fuel the way your manual says, then change the oil, sharpen the blade and bring any battery indoors.

Quick pick: stabilizer for a rider's tank; nothing for a push mower you run dry.

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Drain it or stabilize it? The sources split

Purdue: run it out of fuel; draining beats stabilizer.

Honda manual: over 3 months, run the whole fuel system empty.

Toro Recycler manual: stabilize at the last fill, then run it dry. Stabilized fuel: 90 days at most.

Toro yard guide: empty walk-behinds; stabilize and top off riders.

Briggs & Stratton: store a full tank of treated fuel.

Illinois Extension: either works.

Our read: push mower, run it dry. Rider, treat and top off. Your manual beats both, and Honda's warranty excludes fuel damage from neglected storage.

Stabilizer math

Dose: follow the dose on the bottle, scaled to the gallons you actually pour in.

Fresh gas only: Toro says under 30 days old. Honda says stabilizer won't fix stale gas.

Gas mower checklist

☐ Fuel: run dry or treat. Do this first.

☐ Oil: engine still warm from running dry, then disconnect the spark wire (Toro). Drain; refill with your manual's type (Briggs).

☐ Tip it right: Toro says air filter up, tank dry. Honda says fuel cap side up, valve off. Follow your manual. A push mower lift, like MoJack's, avoids tipping.

☐ Deck: scrape and wipe dry (Toro). Keep water off the air filter (Honda).

☐ Blade: sharpen or replace it (Briggs). Wear gloves (Toro).

☐ Spark plug: clean or replace it (Illinois).

☐ Store it: level and ventilated, away from furnaces, water heaters and dryers (Honda). No sheet plastic over it; it traps moisture (Honda).

Which steps fit your mower

Gas push mower: run dry, then the full checklist.

Rider or zero-turn: treat and top off, then oil, blade and battery.

Battery mower: clean it, sharpen the blade, bring the pack in.

Not a fit: stabilizer in a tank that has sat for months. Drain that gas instead.

Batteries

Rider's starter battery: disconnect negative first, then positive, and store it cool and dry, away from gas cans (Briggs).

Lithium pack: bring it indoors. Consumer Reports says most do best at 40 to 80°F and near 40 percent charge. Check your manual.

Winterizing tools (#ad)

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Sharp Pebble Cordless Mower Blade Sharpener: for standard home blades, not zero-turn blades, per the maker. See it on Amazon

VEVOR Ride-On Lawn Mower Lift Jack, 880 lb: telescoping, for riders and zero-turns; lifts the mower for blade and deck work, per the maker. See it on Amazon

NOCO GENIUS2 Battery Maintainer: the low-cost pick. 2 A, 6 and 12 volt, for a rider's starter battery, not a lithium pack. See it on Amazon

Lawn mower winterizing FAQ

Should I drain the gas from my lawn mower for winter?

For a push mower, yes, unless your manual says otherwise (Purdue, Honda, Toro).

Is it OK to leave gas in a mower over winter?

Only stabilized, if your manual allows it. Honda and Toro's Recycler manual stop at about 3 months.

Do I need to take the battery out of a riding mower?

Briggs says yes. Toro says remove it unless you start the mower during winter.

Next: fall lawn fertilizer and dormant seeding.

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Sources: Illinois Extension, 2018; Purdue; Honda manual, 2013; Toro manual; Toro guide; Briggs & Stratton; Consumer Reports, 2018.