Every maintenance checklist has its tipping point, where the complexity of the task starts to outweigh the likelihood of your ever completing the work. So it is with winterizing a lawn mower. In researching this topic, I confronted myriad steps and conditions, things like gapping the spark plug and cleaning the air filter (unless the filter is made of paper, in which case you need to replace it). All in all, a lot to think about for a supposedly routine procedure.
Wanting to clarify and shorten the list, I turned to Peter Sawchuk, a program leader in our technical division. He designed outdoor power equipment for more than 20 years before joining Consumer Reports, so he’s a mower-maintenance maven.
Sawchuk had already developed a two-tiered, end-of-season checklist for lawn mower and tractor maintenance. The first tier covers steps you have to take to ensure that your machine will start up next spring. They’ll cost you a few bucks and maybe an hour of your time.
The second tier includes things you should do if time permits or if it’s been several years since you last tuned up your mower. “Take something like spark plugs,” explains Sawchuk. “On a good mower, they should last a few years, so you don’t need to worry about replacing them every winter.”
What I ended up with is this prioritized checklist that should make this winterizing task more manageable, freeing you up for other jobs, like raking leaves.
If you’re in the market for a new machine—take advantage of season-ending sales—read our latest report and use our Ratings of push and self-propelled mowers, and lawn tractors to find the right mower for your yard.—Daniel DiClerico
Stabilize the fuel. Gas that sits in a mower all winter can clog the carburetor. Come spring, you’ll have to pay upwards of $100 to have the part professionally cleaned.
If you store the mower in the basement, run the engine until the gas is gone. If you keep it in the garage, fill the tank (to prevent condensation) and add a bit of fuel stabilizer, available at home centers and gas stations.
Add stabilizer every time you fill up your gas container since it helps engines run cleaner. This time around, remember to operate the mower for 5 minutes so that the stabilizer can reach the carburetor. (Tip: Whether you keep the mower in the basement or the garage, stick a cup full of mothballs near the engine to prevent rodents from nesting there.)
Change the oil. Routine oil changes will extend the life of the engine. Be sure to refill the oil reservoir to the designated mark on the dipstick, remembering that too much oil can be as bad for the engine as too little. (To dispose old oil properly, take it to a local service station or recycling center.)
Charge the battery. If your mower or tractor has a battery-powered starter system, periodically charge the battery throughout the winter. Otherwise, it will fail much sooner because it will not hold a full charge. Unlike your car, mower engines can not fully recharge your battery while mowing.
Clear the deck. Scrape grass clippings from the underside of the mower deck to prevent it from rusting. If you do this right after the final mow, spray from a garden hose should be enough to clear the clippings. Otherwise, an old bristled pot scrubber is an effective tool. Spray the cleaned deck with silicone spray to help prevent future build-up.
Replace the spark plug(s). Spark plugs typically need replacing every 100 hours of operation. (Tip: Buy an hour meter at the home center or parts supplier to keep track of running time.) You’ll know right away from the corrosion if yours is spent. If the plug is in good shape, it’s a good idea to remove it, pour an ounce of motor oil into the cylinders, crank the engine a few times, and then reinstall the plug.
Sharpen blades. Save yourself the hassle next spring by getting your blades sharpened now. Keep a second blade on hand for when the first one is being sharpened. Change blades every month during the mowing season to keep dull blades from butchering grass.
Service the air filter. Refer to the owner’s manual to see if you should clean or replace the filter and how frequently.
Replace the fuel filter. Refer to the owner’s manual for specific instructions. Mowers usually don’t have a fuel filter, though many lawn tractors do.