How to start and winterize a lawn mower
Most mowers that will not start have old gas in them, so begin each season with fresh fuel, checked oil and a clean air filter, then prime, set the choke and pull. To winterize, add fuel stabilizer and run the engine a few minutes or run it dry, change the oil, pull the spark plug wire, and clean and sharpen the blade.
About 30 minutes to learnTake care: injury or damage if careless
Mark it once you can do it without this page open.
How to do it
- Pull the spark plug wire off the plug before you touch the blade or tip the mower for any reason.
- Drain or run out gas more than a month old, and refill with fresh fuel, adding stabilizer if it will sit.
- Check the oil on the dipstick and top it up with the type the manual names.
- Tap out or replace the air filter if it is clogged.
- Reconnect the plug wire, press the primer bulb as the manual says, set the choke, and pull the cord in a smooth, firm stroke.
- At the end of the season, add stabilizer and run the engine five minutes, or run the tank dry.
- Change the oil, then disconnect the plug wire, scrape the grass off under the deck and sharpen or replace the blade.
- Store the mower dry, and the fuel can in a ventilated shed, never beside a furnace or water heater.
Stop and call a professional if
- The mower still will not start with fresh fuel, a clean filter and a good plug.
- It smokes heavily, leaks fuel or makes knocking noises.
- The blade is bent or the crankshaft wobbles after hitting something.
Common mistakes
- Leaving summer gas in the tank all winter.
- Tipping the mower with the carburetor side down, which floods it with oil.
- Working on the blade with the spark plug connected.
- Refueling a hot engine.
Quick self-check
Three questions. Your last score is kept in this browser.
Teach this to someone
A one-page sheet for showing a friend, a roommate or a kid: what to say, what to show, and one question to check it landed.
Teach: How to start and winterize a lawn mower
What to say
Most mowers that will not start have old gas in them, so begin each season with fresh fuel, checked oil and a clean air filter, then prime, set the choke and pull. To winterize, add fuel stabilizer and run the engine a few minutes or run it dry, change the oil, pull the spark plug wire, and clean and sharpen the blade.
What to show, in order
- Pull the spark plug wire off the plug before you touch the blade or tip the mower for any reason.
- Drain or run out gas more than a month old, and refill with fresh fuel, adding stabilizer if it will sit.
- Check the oil on the dipstick and top it up with the type the manual names.
- Tap out or replace the air filter if it is clogged.
- Reconnect the plug wire, press the primer bulb as the manual says, set the choke, and pull the cord in a smooth, firm stroke.
- At the end of the season, add stabilizer and run the engine five minutes, or run the tank dry.
- Change the oil, then disconnect the plug wire, scrape the grass off under the deck and sharpen or replace the blade.
- Store the mower dry, and the fuel can in a ventilated shed, never beside a furnace or water heater.
When to stop and call a professional
- The mower still will not start with fresh fuel, a clean filter and a good plug.
- It smokes heavily, leaks fuel or makes knocking noises.
- The blade is bent or the crankshaft wobbles after hitting something.
The check question
Ask: What do you disconnect before touching the blade?
Related skills
- How to mow a lawn properly
- How to check engine oil
- How to sharpen a knife
- Every skill in Yard, Garage and Seasons
Words on this page
Sources
- The equipment maker's operator manual, for your model. Checked September 28, 2026.
Last reviewed . First published .