How to service the mower and outdoor power tools
For spring lawn mower maintenance, disconnect the spark plug before the first cut and drain any fuel that sat all winter. Change the oil, fit a new plug and air filter, then sharpen the blade and clean the deck. Refill with fresh 87-octane gas containing no more than 10% ethanol. Most owners can finish in an afternoon.
Spring lawn mower maintenance schedule
Your owner's manual overrides everything here, and hour counts matter more if you have a big yard. For a typical walk-behind gas mower, these are common intervals.
| Job | Interval |
|---|---|
| Check oil level | Before each use |
| Change oil | Start of each season, or about every 25 hours of use |
| Replace spark plug | Start of each season, or about every 25 hours of use |
| Replace air filter | About once a year |
| Sharpen blade | Once or twice a season |
| Clean under the deck | After each use if you can, and always in spring |
Fuel is the part people skip. Briggs & Stratton says gas can degrade in as little as 30 days, which clogs the fuel system. That's why anything left in the tank since fall comes out first.
What you need for a lawn mower tune-up
- The owner's manual, for oil type, oil amount and plug number
- Fresh oil, a new spark plug and an air filter
- A spark plug socket and a wrench for the blade nut
- A drain pan and a sealed container for old oil
- A clamp or vise, a metal file, gloves and eye protection
- Fresh gas and fuel stabilizer
Never pour used oil on the ground or down a drain. EPA treats it as household hazardous waste, and some auto garages will take it.
How to tune up a lawn mower in spring
- Make the mower safe
Work with a cool engine on a flat surface. Pull the spark plug wire before you touch the blade or drain anything, so the engine can't start by accident.
- Empty old fuel
If the gas sat all winter, drain it into an approved container and take it to a hazardous waste collection.
- Change the oil
Run the engine briefly first so the oil flows, then shut it off and pull the plug wire again. Drain, then refill with the grade and amount in your manual.
- Fit a new plug and filter
Install the plug number your manual lists, and replace the air filter. Reconnect the wire only when all the other work is done.
- Sharpen the blade
Tip the mower with the carburetor side up, mark the blade's outer face, and remove it. Clamp it and file along the bevel at its original angle, then refit it with the mark facing out.
- Scrape the deck
Remove built-up grass from under the deck. Exmark suggests a wax coating to help keep debris from sticking.
- Refuel and test
Use unleaded gas rated at least 87 octane and no more than 10% ethanol. Add stabilizer if it will sit. Check the oil level again and start the engine.
- Wake up the other tools
Start the trimmer, blower and chainsaw. Refill trimmer line, check the saw chain, and follow each manual for fuel mix and service.
Warning signs during spring lawn mower maintenance
Stop mowing and look into it if you notice any of these:
- Misfiring, lost power, odd noises or a strong fuel smell. A clogged air filter is one common cause.
- Flames or black smoke from the engine
- Hard starting and high fuel use, which can mean a failing plug
- A cracked or chipped plug
- Grass with brown, torn tips and an uneven cut. The blade is dull.
- A bent, warped or badly nicked blade. Replace it rather than filing it.
Do a lawn mower tune-up yourself or go to a shop?
A basic tune-up is well within reach for a first-time owner. Take the mower to a dealer or small-engine shop if it won't start with fresh fuel and a new plug, if you find fuel leaks, or if the blade spins out of balance after sharpening.
Electric mowers skip the oil, gas and plug. Remove the battery or unplug the mower before you touch the blade, and wipe the deck with a damp cloth. Don't hose it down, because water can short the electrics. For riding mowers, also check tire pressure against the number on the sidewall, and replace worn belts.
When to change lawn mower oil, and other questions
How often should I change my lawn mower oil?
At the start of each season or about every 25 hours of use, whichever comes first. Check your manual, since engines differ, and check the dipstick before each use.
Which way do you tip a lawn mower?
Keep the carburetor side up. Tipping the other way can send oil and fuel where they shouldn't go. Disconnect the spark plug wire first.
Can I use last year's gas in my mower?
It's best not to. Gas can degrade in as little as 30 days. Drain it, refill with fresh fuel, and use a stabilizer if the mower will sit for long.
Sources: backyard.exmark.com, briggsandstratton.com, Bob Vila, EPA
General guidance for U.S. homes, not professional advice. For gas, electrical and structural work, call a licensed pro.