Winterizing a Lawn Mower: The Steps That Save a Spring Repair Bill

Finishing the last mow of the season feels like the finish line, but it isn't — not if I want the mower to start on the first pull next spring. The single most common way a lawn mower dies isn't hard use, it's neglect over winter: old gas gumming up the carburetor, moisture rusting the blades, grime caking the deck. Spend twenty minutes winterizing it properly and I save myself hundreds of dollars in repairs and add years to the machine's life. Skip it and I'm often shopping for a new mower come April.

This is a job worth doing carefully and in order. None of the steps are difficult, but each one heads off a specific failure that I've either suffered myself or watched a neighbor pay for. Here's the sequence I follow before the mower goes into storage.

Empty the gas tank first

Old gasoline is the number one mower killer. Left to sit all winter, it breaks down and turns to a varnish-like gunk that clogs the carburetor, and clearing that out is exactly the kind of repair that runs into real money. So before anything else, I run the tank dry — I start the mower and let it run until it consumes all the remaining fuel and stalls on its own. To confirm it's truly empty, I try to restart it; if it won't fire, the tank's drained and I've done it right.

If I'd rather store it with fuel, the alternative is treating a full tank with fuel stabilizer so the gas doesn't degrade. But for a small mower, running it dry is the simplest, surest route.

Change the oil and the air filter

Next I refill with fresh oil — a sensible amount, not overfilled, not low. A season's worth of lawn mower oil is full of grit and acids that corrode the engine if left in over winter, so swapping it out now protects the internals during the long idle. I dispose of the old oil the right way, taking it to a station that collects it rather than pouring it down a drain, a sewer, or onto the ground.

While I'm at it, I deal with the air filter. If it's a plastic-framed foam type I can clean it; if it's paper, I just replace it. A fresh lawn mower air filter at least once a season keeps the engine breathing properly, and winterization is a natural time to do it.

Pull the spark plug, oil the cylinder, clean the deck

I remove the spark plug, pour a little lubricating oil into the plug hole, and crank the engine a few times by hand to spread that oil around inside the cylinder — it coats the internals so they don't rust while the mower sits. Then the plug goes back in. If the plug's old (a rough guideline is around a hundred hours of use), I swap in a new spark plug instead of reinstalling a worn one.

Then I flip the mower and clean the underside of the deck. Grass clippings pack up between the blades and against the housing, and that wet matted material is what causes rust over winter. I scrape it off, hose it down, and scrub away any greasy buildup with warm soapy water, using steel wool on any rust spots. Then I let it dry completely before storing — and I always wear work gloves around the blades, because a clean job isn't worth a sliced hand.

Sharpen the blades and store it safe

Winterizing is the ideal time to sharpen the blades, because I can do it now at my leisure instead of scrambling on the first warm day of spring. I sharpen them myself or send them out, then wipe on a film of protective oil so they don't rust during the layup. A sharp, oiled blade ready to go is one less thing standing between me and the first cut of the season.

Finally, the mower goes somewhere safe and dry — the garage, the basement, wherever it's protected. I cover it to keep dust off and tuck a couple of mothballs nearby so mice don't decide the engine compartment makes a cozy winter nest. A mower put away clean, dry, drained, and oiled is a mower that starts on the first pull in spring, which is the whole reason I bother with any of this.