How often should you winterize your mower?
Grumpty's answer
Every 12 months
Why bother
Stale fuel gums the carburetor over a cold winter. A thorough-tier job. Skippable when life's busy, worth it when it isn't.
Why it's a range
Warm regions that mow year-round can skip it.
What the job involves
- Sort the fuel first. Either run the tank dry, or fill up with fresh gas, add stabilizer, and run the engine about 10 minutes so the treated fuel reaches the carburetor. Don't bother stabilizing old gas. It won't come back.
- Change the oil while the engine's still warm from running, so the dirt and acids don't sit and eat at the insides all winter.
- Clean or swap the air filter, scrape the matted clippings off the deck and underside, and every season or two put in a fresh spark plug.
- Park it somewhere dry, a garage or shed. A full stabilized tank keeps condensation from forming inside, which is the other thing that does mowers in.
Do it yourself, or pay someone?
Yourself. A bottle of stabilizer and a quart of oil run about $15 to $25, plus half an hour. A shop doing the full end-of-season prep instead runs $50 to $100 for a push mower, $140 to $170 for a riding one.
What skipping it costs
$40 to $120 is the usual spring fix: a pro cleaning the carburetor after winterizing got skipped. Bob Vila puts a simple clean at the low end, around $36 to $50; This Old House and Family Handyman cite $75 to $100 for the same job once the gummed fuel has had all winter to set. Some shops add $30 to $70 for pickup and delivery on top. If the carburetor's too corroded to clean, you're paying for a new part and the labor to fit it. A bottle of stabilizer is cheaper than any of that.
Signs it's overdue
- Last fall's gas is still in the tank and it never got run dry or stabilized.
- It's hard to start, sputters, or won't keep running on the first go in spring.
- There's a sour, varnish-like whiff of old gas, or gummy residue down in the tank or carburetor bowl.
When to start thinking about it
A few days' warning does it. Grumpty grumbles 5 days out, then leaves you alone. Mark it done and Grumpty sets the next one, every 12 months, so you can go back to forgetting it exists.
Questions people ask
How often does the mower need winterizing?
Once a year, at the end of the mowing season, before it sits unused for the cold months. The trigger is the sitting, not the date. Once fuel's going to sit for more than about 30 to 90 days, either run the tank dry or fill it with fresh stabilized gas.
Do I really need fuel stabilizer, or can I leave the gas in?
Leaving untreated gas in is the main reason a mower won't start come spring. The ethanol in pump gas pulls in water and separates over winter, gumming up and corroding the carburetor and fuel lines. So either run the system dry or use stabilizer in a full tank of fresh gas. Ethanol-free gas stores better, but it costs more and not everywhere sells it.
What's it cost if I skip it and the mower won't start in spring?
Usually $40 to $100 for a shop to clean the carburetor, plus pickup and delivery at some places. If it's too gummed or corroded to clean, you're into a replacement, part plus labor, which runs higher. Mower repair averages around $60 either way, per Bob Vila. The stabilizer would have been a few dollars.
Related jobs
Stop keeping this one in your head
This is one job. Your home has dozens more, each on its own clock. Grumpty is a free home-maintenance app: add a job once, it tracks the date, grumbles when it's due, and rolls it forward the moment you mark it done.
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