Winterizing Your Outdoor Power Equipment: A Complete End-of-Season Checklist
Every fall, a predictable wave of 'it won't start' questions shows up about mowers, generators, and trimmers that sat all winter with no prep. Almost all of it traces back to the same two causes: stale fuel and batteries that were stored the wrong way.
None of the fixes below take more than a few minutes per machine, and doing them now is a lot cheaper than a carburetor cleaning or a dead battery pack in the spring.
Why winter storage damage happens
Modern gasoline, especially ethanol-blended E10, starts breaking down within a month or two. It absorbs moisture, separates, and leaves behind a gummy residue that clogs small carburetor passages — the number one reason small engines refuse to start after sitting all winter.
Lithium-ion batteries have a different problem: they slowly self-discharge, and storing one fully charged or fully dead for months accelerates capacity loss. Cold, damp air adds a third issue for everything with bare metal parts — blades, chains, and fasteners rust faster than most people expect.
Gas engines: stabilize the fuel or drain it
For mowers, trimmers, chainsaws, gas pressure washers, and generators, treat the fuel first — it matters more than anything else on this list. You have two solid options: fill the tank, add a fuel stabilizer, and run the engine for a few minutes so treated fuel reaches the carburetor; or run the tank dry and let the engine die on its own.
Either approach works. Topping off with stabilizer is usually easier, while running dry is a good choice for equipment that won't be touched again until spring cross-country trips or storm season.
If you're still deciding between a gas and an electric model in the first place, our guide to gas vs. electric pressure washers breaks down how much of this seasonal fuel maintenance you can skip entirely by going electric.
Battery-powered tools: store at a partial charge
For cordless mowers, trimmers, blowers, and chainsaws, don't store the battery at 100% or at 0% for months at a time — both extremes shorten its usable life. Most manufacturers recommend storing lithium-ion packs around 30-50% charge.
Keep batteries somewhere moderate in temperature rather than an unheated garage or shed if you can, and check them every couple of months over winter, topping off if they've drained further than expected.
Portable generators need a slightly different approach
The fuel-stabilizer-or-drain rule applies to generators too, but the right call depends on how you use one. If it's strictly for occasional or recreational use, draining the tank and running the carburetor dry is the cleanest way to store it.
If you keep a generator ready for winter storm outages, don't drain it completely — add stabilizer to the fuel instead and start it up briefly once a month so it's ready the moment you actually need it.
If you haven't sized a generator for your home yet, our What Size Generator Do I Need? guide walks through matching running and starting watts to your household so you're not guessing.
Clean blades, chains, and housings before they sit
Grass clippings, sap, and dirt hold moisture against metal and accelerate rust over a winter of sitting untouched. Clean housings and undersides thoroughly, sharpen and lightly oil mower blades and chainsaw chains, and wipe down any bare metal with a light coat of oil.
It's also a good time to check air filters and spark plugs on gas equipment — both are cheap to replace now and annoying to discover fouled on the first warm day of spring.
Where to store everything
Keep equipment off a bare concrete floor where moisture collects, and away from direct contact with an exterior wall in an unheated space. Shelving keeps mowers, generators, and bins of accessories organized and out of the way of a car door or foot traffic.
If your garage storage is more pile-on-the-floor than system, our garage storage and shelving buying guide covers freestanding shelving, wall-mounted systems, and overhead racks — and how to plan around per-shelf weight limits before you load anything heavy.
Frequently Asked Questions
- Do I need fuel stabilizer if my gas station sells ethanol-free fuel?
- Ethanol-free fuel resists gumming better than standard E10, but it still oxidizes and degrades over months of storage. Stabilizer is inexpensive insurance either way.
- How long can I leave a battery in a cordless mower or trimmer?
- It's fine short-term, but for winter-long storage it's better to remove the battery, charge it to roughly 30-50%, and keep it somewhere moderate in temperature rather than leaving it in the tool in a cold garage.
- Should I run a generator's tank completely dry before storing it?
- For occasional-use generators, yes — drain the tank, add stabilizer to any leftover fuel, and run the carburetor dry. For a generator you're keeping ready for storm season, add stabilizer and start it monthly instead so it's ready when you need it.
- Can gas equipment be stored safely in an attached garage over winter?
- Yes, as long as fuel is stabilized or drained and any stored fuel containers are sealed and approved for gasoline. The bigger risk is fumes from open or leaking containers, not the equipment itself.