Winterizing Outdoor Power Equipment This Fall: Mower, Chainsaw, Batteries and Tractor

Winterizing comes down to three things: don't leave old fuel in a small engine, don't store lithium batteries full or empty, and don't let a tractor's coolant, battery or fuel tank face the cold unprepared. According to L'Atelier, 90% of spring "it won't start" mower problems come from degraded fuel left in the tank and carburetor over winter. Here is the routine for each machine, with the values the sources give.

Gas lawn mower: the 5-step winterization

L'Atelier's mower guide reduces winter storage to five steps. Do them right after the last mow, while the engine is still warm.

The one thing never to do, in the guide's words: leave ordinary gas sitting all winter with nothing added. It is the number one cause of gummed-up carburetors. For storage, keep the mower somewhere dry, store it with the blade flat (not on edge), and if it has an electric starter, disconnect the battery and keep it warm.

The last mow of the year

Set the deck for about 4-5 cm on the final cut, one setting shorter than your summer height, once growth has slowed and in dry conditions. Too short exposes roots to frost and encourages moss; too long, the grass gets flattened by snow and moisture and rots. The source, written for European lawns, places that last cut "often late October to November depending on region"; judge by when growth slows where you live. After the mow, clean under the deck (trapped grass holds moisture and rusts the deck), check blade sharpness, and check the oil level before the winter drain. To sharpen, disconnect the spark plug lead first, keep the original angle and rebalance the blade.

Chainsaw winter storage

L'Atelier's complete chainsaw guide applies its storage routine as soon as the saw will sit for more than 30 days:

1. Empty the fuel tank and run the engine until it stops from fuel starvation, so the carburetor is dry.
2. Oil the cylinder: remove the plug, add a few drops of 2-stroke oil (the season guide says 1-2 ml), pull the starter 2-3 times, refit the plug.
3. Clean the air filter and refit it dry.
4. Remove the bar and chain, clean the bar groove, oil the chain and bar and store them separately in a dry place.
5. Clean the housing and cooling fins of sawdust.
6. Store dry and frost-free, with the bar cover on.

In spring: refit bar and chain at the correct tension, fill with fresh mix only, check the chain brake and inertia sensor, and idle 2-3 minutes before cutting. The same approach covers other 2-stroke tools: L'Atelier's hedge trimmer guide asks for cleaned and lubricated blades with the blade guard on plus the 2-stroke steps for gas models, and the brush cutter guide says to drain the tank and run the engine dry before any storage longer than 30 days.

How long does 2-stroke mix keep? The sources disagree

This matters for winter, because whatever mix is left in the can in November will not be fresh in spring. L'Atelier's pages give different limits:

• 30 days maximum: the complete chainsaw guide ("Beyond that, the gasoline degrades") and the Stihl MS 261 mix page ("Old mix (> 30 days): fuel degrades, oil separates").
• A sliding scale: the 2-stroke mixing guide calls 30 days the maximum in its heading, then says under 30 days is normal use, 30-60 days the mix degrades and starting may be difficult, beyond 60 days discard it.
• 6-8 weeks max: the season-by-season chainsaw guide.
• With E10: the fuel page says use E10 mix within 30 days; the mixing guide says within 15 days if you have no alternative.

The common ground is clear enough for winter: no page suggests keeping mix through to spring. The mixing guide adds practical habits: write the preparation date on the container, store it in metal or opaque plastic out of sunlight, and prepare 1-2 liters at a time rather than a large can. It also mentions ethanol-free alkylate fuel, which it says keeps 2 years or more, as the choice for occasional users.

Cordless batteries: partial charge, indoors

• Charge level: the winter storage guide recommends around 40-60%, charging to about 50% before storing. The platforms article gives a wider 40-80% band, ideally 50-60%. Never full, never flat: a battery left empty all winter can discharge deeply and become unrecoverable.
• Where: indoors, in a dry, temperate room, not an uninsulated garage that freezes. The platforms article gives 10-25°C as the target and says below 0°C damages cells.
• How: take the battery out of the tool to avoid constant micro-discharge, and don't stack packs.
• Mid-winter: check once and top up if the level has dropped noticeably (self-discharge is about 1-2% per month).
• Damaged or swollen pack: do not store it, send it for recycling.
• In spring: charge fully before use. A pack that has lost a lot over winter is nearing the end of its life.

Tractor winterization checklist

Whether the tractor sleeps all winter or comes out occasionally, L'Atelier's pre-winter checklist starts with the cooling system: coolant that is too diluted can freeze and crack the block or radiator.

Finish with a complete cleaning to remove dirt and corrosive residue. Come spring, the start-of-season checklist picks up where this one ends: battery above 12.4 V, alternator at 13.8-14.4 V, tires typically down 0.2-0.4 bar.

Common winterizing mistakes

• Leaving gas or 2-stroke mix in a small engine all winter with nothing added.
• Storing cordless batteries on the charger, fully charged, or in a freezing shed.
• Forgetting the rag in the tractor's exhaust in spring.
• Mowing too short on the last cut "to get ahead": frost and moss follow.
• Putting the chainsaw away with the bar on and sawdust packed in the groove and cooling fins.

Not sure of a value for your machine? Ask the L'Atelier power tools and garden machinery base, for example "I'm putting my cordless tools away for the winter. How full should the batteries be?"

Sources on la-telier.com: winterizing a petrol mower, last mow of the year, storing batteries in winter, tractor winterization.