The weather is cooling down, the grass is growing slower, and you’ve just finished the last cut of the season. Your lawn mower is about to enter a few months of “hibernation.” But here’s the thing – just pushing it into a shed and pulling it out again next spring is one of the worst things you can do for your machine.
Winter brings cold and humidity. Leftover gasoline can degrade and form gum that clogs the carburetor. Uncleaned grass clippings hold moisture and cause the deck to rust. Impurities in the old oil settle and corrode internal parts. Come spring, you’ll face a mower that won’t start, vibrates badly, leaks oil… A perfectly good machine can be ruined just by sitting.
The good news? In just one afternoon, following the complete maintenance procedure below, your mower will be ready to start on the first pull next spring. We call it the “pre‑storage ritual.”
Step 1: Full cleaning – Don’t bring dirt and grass into storage
Your mower has worked hard all year. The underside of the deck, cooling fins, area around the air filter, and wheel axles are caked with thick layers of grass and mud.
How to do it:
- Move the mower onto a concrete surface and disconnect the spark plug cap (safety first).
- Tip the mower over (carburetor side up – this prevents oil from flowing into the cylinder) and use a pressure washer or a stiff brush to thoroughly clean the grass buildup under the deck. Dried‑on clumps may need a scraper.
- Wipe down the engine housing, handles, and wheels with a rag. Pay special attention to the cooling fin gaps – if they get clogged, the engine will overheat next summer.
- After rinsing with water, let everything dry completely or wipe it dry. Apply a light mist of rust preventive (WD‑40 works fine) to metal surfaces.
Don’t cut corners: Leftover wet grass acts like a sponge. One winter of that can cause deep rust pitting on your deck.
Step 2: Fuel system treatment – Either add stabilizer or drain completely
Gasoline begins to oxidize after 30 days, producing gum and varnish that clog the tiny jets in the carburetor. This is the #1 reason mowers won’t start in the spring.
Two reliable options – pick one:
Option A (recommended, especially for gasoline engines): Add fuel stabilizer
- Before your last use of the season, add fuel stabilizer to the tank according to the label instructions.
- Run the mower for 3‑5 minutes so that treated gasoline fills the carburetor.
- Then shut it down for storage. Stabilizer keeps fuel fresh for 6‑12 months.
Option B (simple but easy to mess up): Drain the fuel completely
- If the mower won’t be used for several months, you can open the carburetor drain screw and empty both the tank and carburetor into an approved container.
- Important: After draining, pull the starter rope several times to clear any remaining fuel from the carburetor. Leaving even a tiny amount can actually make gummy deposits worse.
Never forget: Do not leave ethanol‑blended gasoline (E10) sitting in your mower for months. Ethanol absorbs moisture and corrodes carburetor parts. If you can’t guarantee pure gasoline, either drain it or use stabilizer.
Step 3: Oil change – Don’t let dirty oil corrode all winter
Your oil has been through a season of high heat, collecting metal particles, carbon, and moisture. If left unchanged, these acidic contaminants slowly eat away at the crankshaft, cylinder walls, and bearings.
How to do it:
- Change the oil while the engine is warm (drain it right after shutting down – it flows better and carries suspended impurities).
- Remove the drain plug and let the old oil run out completely. If your engine has a fill neck, you can also use a syringe or manual pump.
- Refill with new oil that meets the viscosity grade in your owner’s manual (most commercial mowers use SAE 30 in summer, 10W‑30 in fall/winter).
- Fill to just below the full mark on the dipstick. Start the engine and let it run for 30 seconds, then stop and recheck the level.
Step 4: Spark plug inspection and replacement
Remove the spark plug and look at the electrode color:
- Normal: Light brown or brick red.
- Black soot: Air‑fuel mixture too rich, or dirty air filter. Clean or adjust.
- White: Overheating or mixture too lean – needs checking.
- Burnt electrode or excessive gap: Replace with a new plug. A spark plug is cheap – don’t skimp.
Pro tip: Put a tiny dab of anti‑seize compound on the threads before reinstalling the plug. It won’t seize up next year when you remove it.
Step 5: Blade and deck – Sharpen now, save time later
While the season is still fresh in your mind, remove the blade and inspect it:
- Any nicks, bends, or cracks? Replace it.
- Dull? Use a file or angle grinder to sharpen it to the original angle. Don’t forget balance – put the blade on a screwdriver; if one side drops, grind that side a bit more.
- Retighten the blade bolt to the specified torque.
After cleaning the underside of the deck, you can spray on a deck protection paint or anti‑rust wax. This dramatically extends deck life.
Step 6: Battery (for electric‑start models)
Lead‑acid and lithium batteries self‑discharge quickly in cold temperatures. If they go completely flat, they can sulfate or become damaged.
What to do:
- Remove the battery from the mower. Wipe off any corrosion on the terminals with a damp rag.
- Fully charge the battery with a proper charger (don’t overcharge).
- Store it in a dry, frost‑free place (room temperature is best). Give it a top‑up charge once a month.
- Or keep it connected to an intelligent trickle charger/maintainer.
Step 7: Choose the right storage environment
- Best choice: A dry, well‑ventilated indoor shed or garage with stable temperature.
- Avoid: Storing directly on dirt, in damp corners, or in uninsulated shelters that freeze.
- Cover: Use a breathable canvas tarp or an old bedsheet to keep dust off. Do not seal it tightly with plastic – that traps condensation.
Extra tip for tires: Don’t let them sit in one spot for months. If possible, put the mower up on blocks to take weight off the wheels, or roll it a few inches every month to prevent flat spots.
Quick spring start‑up checklist
When the snow melts and the grass turns green again, don’t just yank the rope. Do these checks first:
- Check oil and fuel (if you used stabilizer, it’s ready; if you drained, add fresh fuel).
- Inspect the air filter – is it damp or did mice nest in it?
- Check all bolts, the blade, and belts for looseness.
- Remove the spark plug, pull the starter rope several times to blow out any storage oil or moisture from the cylinder, then reinstall the plug.
- After starting, let the engine idle for 2 minutes to circulate oil before working it hard.
Final summary
Think of your mower as a member of your crew. Give it a good winter’s sleep, and it will have the energy to earn you money next year. The seven steps above – clean, fuel treatment, oil change, spark plug, blade, battery, storage – take about two hours and cost very little. They will save you hundreds in repair bills and weeks of waiting next spring.
If you found this guide useful, please save it or share it with fellow landscapers. And feel free to share your own maintenance tips. We wish you and your mower a peaceful winter, and a spring full of full‑throttle power.
