How-to Guide
Winterizing the Lawn Mower and Power Tools
The short answer
The number-one cause of a mower that won't start in spring is degraded fuel. Extension and manufacturer guidance agree gasoline can begin to break down in as little as 30 days, gumming up the fuel system. You have two accepted options: add fuel stabilizer to a full tank and run the engine a few minutes so treated fuel circulates through the carburetor, or drain the fuel system completely.
Beyond fuel, do the rest of the fall service: change the engine oil, clean grass and debris off the deck and undercarriage, and check or replace the air filter. Remove the battery from riding and cordless machines and store it in a cool, dry place kept above about 40 degrees Fahrenheit, since cold and a connected circuit both drain it.
Finish by sharpening the blade now so the tool is ready to cut cleanly in spring; see sharpening-lawn-mower-blades and the broader garden-tool-care for hand tools.
Fuel: stabilize or drain (pick one)
Gasoline left in a tank oxidizes and leaves gum and varnish that clog the carburetor. UGA and other extension sources note gasoline begins to degrade in as little as 30 days, which is why a mower parked in October often won't start in April. Choose one of two paths and commit to it.
Stabilizer path: add fuel stabilizer to a full or nearly full tank and run the engine for a few minutes so the treated fuel reaches the entire fuel system including the carburetor. A full, stabilized tank also limits condensation and rust inside the tank. Drain path: run the tank dry or empty it into an approved container so no fuel is left to degrade. Both are legitimate; the failure mode is doing neither and leaving untreated gas to sit.
For two-stroke tools (string trimmers, blowers), the same fuel logic applies, and running the carburetor dry is common practice for small handheld units.
Oil, deck, and filters
Fall is a good time to change the engine oil so the machine sits over winter on clean oil rather than acid-laden used oil. Clean caked grass off the deck and underside; damp clippings hold moisture that promotes rust on the deck and blade. Check the air filter and fuel filter and replace them if dirty, since a once-a-year replacement keeps the engine running well.
Wipe the machine down and store it somewhere dry. These are manufacturer-neutral steps echoed across extension winter-storage guidance.
Battery and blade
Remove the battery from riding mowers and cordless machines. Both 12-volt and lithium-ion batteries self-discharge when left connected, and cold accelerates the loss, so store the battery indoors in a cool, dry place kept above about 40 degrees Fahrenheit and away from fuel and heat sources. Lithium-ion packs store best at a partial charge rather than fully drained.
Sharpen the blade before storage so it is ready in spring, and always pull the spark-plug wire (or remove the battery on cordless units) before touching the blade. The full sharpening procedure, including balancing and how often to sharpen, is in sharpening-lawn-mower-blades.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- University of Wisconsin-Madison Extension (Chippewa County) — Cleaning garden equipment for winter storage — Extension guidance on cleaning and winterizing garden equipment for storage: clean debris from equipment, handle fuel before storage, and service machines so they are ready for the next season
- University of Georgia Cooperative Extension — Winterizing motorized equipment — Gasoline begins to degrade in as little as 30 days, which can clog the fuel system; add fuel stabilizer when filling the tank for the last time each year and run the engine a few minutes to distribute stabilized fuel; storing with a full tank of treated fuel prevents moisture condensation and rust; replace fuel and air filters at least once per year; remove the battery and store it in a cool, dry place away from gas cans and heat sources