The last mow of the year takes maybe 45 minutes. Proper winterization takes about the same — but only if you do it. The number of mowers that come into dealerships every spring with a varnished carburetor, a dead battery, cracked belts, and dull blades would be cut in half if people spent an hour at the end of the previous season doing the things on this list.

This guide covers everything: fuel treatment, battery storage, deck inspection, blades, belts, spindles, engine service, hydraulics, and tire pressure. Work through it once and you’ll park a healthy machine. Pull it out in the spring and it’ll start clean.

🗒️ WINTERIZATION CHECKLIST — Print and Work Through It
  • Add fuel stabilizer to tank and run engine to circulate treated fuel through the system
  • Choose fuel strategy: stabilize, drain, or switch to ethanol-free for last few tanks
  • Keep only a minimal amount of fuel in the tank over winter
  • Disconnect battery and connect to trickle/float charger for winter storage
  • Perform engine oil change (and filter if applicable)
  • Check and change hydraulic fluid if required; check level when cold if not
  • Inspect and sharpen or replace mower blades; consider buying a spare set
  • Inspect all deck belts — inside surface for cuts; outside for fraying or dry rot cracks
  • Spin all spindle pulleys by hand — check for noise, catches, or rough spots
  • Spin all idler and deck pulleys by hand — check for wobble or resistance
  • Check tire pressure on all four tires and equalize
  • Clean underside of deck if not already done
  • Grease spindle zerks, wheel bearings, and any other grease fittings
  • Store in a dry, covered location — out of weather if possible

01 Fuel — Your Most Important Step

Fuel problems are the leading cause of spring startup issues. Ethanol-blended gasoline starts to degrade in as little as 30 days, and over a full winter it separates, attracts moisture, and leaves behind a sticky varnish residue that coats every passage in your carburetor or fuel injection system. This is preventable.

OPTION A — FUEL STABILIZER

Treat the Fuel and Run It Through the System

Add a quality fuel stabilizer to the tank — Sea Foam, Star Tron, STA-BIL 360, or similar. Then run the engine for at least 5–10 minutes after adding it. This is the step most people skip: adding stabilizer to the tank but not running the engine means the treated fuel never reaches the carburetor, fuel lines, or injectors. The components that actually need protection over winter never get treated.

Keep only a minimal amount of fuel in the tank over winter — just enough to keep the tank from collecting condensation. A full tank of treated fuel will last, but the less fuel you have sitting, the lower the risk of it going stale if the stabilizer doesn’t fully do its job.

OPTION B — DRAIN THE FUEL SYSTEM

Shut Off the Valve and Run It Dry

If your mower has a fuel shutoff valve, turn it to the off position and run the engine until it dies on its own — this purges the fuel from the lines, carburetor bowl, and any carb-side passages. No fuel left behind means no varnish buildup over winter.

This approach works well for carbureted engines. It takes a few extra minutes but is highly effective. If you don’t have a shutoff valve, you can use a hand pump or siphon to remove fuel from the tank before running the engine dry.

OPTION C — ETHANOL-FREE FUEL FOR THE LAST FEW TANKS

Switch to Non-Ethanol Fuel Late in the Season

Some people make a habit of switching to ethanol-free premium fuel toward the end of the mowing season. Non-ethanol fuel has a longer shelf life, doesn’t attract moisture the way ethanol blends do, and leaves behind far less varnish when it eventually evaporates. Running two or three tanks of ethanol-free fuel through the system before storage essentially flushes the ethanol-blended residue out and leaves your fuel system in much better shape over the winter.

It costs more per gallon, but compared to a carburetor cleaning or replacement in the spring, it’s cheap. Many gas stations and outdoor power equipment dealers stock ethanol-free fuel specifically for small engines.

02 Battery — Don’t Let Cold Weather Drain It

A mower battery left connected and sitting in a cold garage or shed over winter will slowly discharge. Cold temperatures accelerate self-discharge, and a battery that’s allowed to go completely flat over winter will often never fully recover — its capacity is permanently reduced. This is an easy and inexpensive problem to prevent.

STEP 1

Disconnect the Battery

Disconnect the negative terminal first, then the positive. Remove the battery from the mower if possible — storing it indoors at a stable temperature is better than leaving it in the machine in an unheated garage where temperatures swing dramatically.

STEP 2

Connect a Trickle Charger or Float Charger

A float charger (also called a maintenance charger or trickle charger) is a small device that connects to the battery and keeps it at full charge without overcharging it. Unlike a standard battery charger that you disconnect after a few hours, a float charger is designed to stay connected for weeks or months. It monitors voltage and only delivers current when the battery needs it.

Connect it, leave it plugged in, and come back in the spring with a fully charged battery. Battery tenders are available for under $30 and will extend the life of your mower battery significantly.

✅ Pro Tip — Battery Tender vs. Trickle Charger

A true battery tender or float charger is not the same as a basic trickle charger. A basic trickle charger delivers a constant low current and will overcharge the battery if left connected for months. A battery tender is smart — it charges to full and then switches to maintenance mode, monitoring voltage and topping off only when needed. The NOCO Genius, Battery Tender Plus, and Deltran brands are all well regarded. Spend the extra $10–15 for a smart charger.

03 Deck Inspection — Belts, Spindles, and Pulleys

The end of the season is the right time to inspect your deck drive components. If something is worn or about to fail, you want to know now — not when you’re trying to mow in the spring and a belt breaks or a spindle lets go.

STEP 1

Inspect the Deck Belts

Remove the deck belt covers if your machine has them and look at each belt carefully. You’re checking two surfaces:

  • Inside (ribbed) surface: Look for cuts, nicks, missing sections, or glazing. A glazed belt has lost its grip and will slip under load even if it looks intact.
  • Outside surface: Look for cracks in the rubber, dry rot, and fraying along the edges where the belt runs over pulley flanges. Small cracks that run across the belt are a sign of dry rot — the belt looks fine but it’s about to fail.

If a belt shows any of these signs, replace it before spring. Belts are inexpensive compared to the repair bill if a failed belt damages a spindle or gets wrapped around a deck component mid-season.

STEP 2

Spin the Spindles and Pulleys by Hand

With the belt off each spindle, spin the spindle pulley by hand. A good spindle should spin smoothly and quietly with no resistance, no grinding, and no catching. What you’re feeling for:

  • Grinding or roughness: Bearing wear — replace the spindle
  • A catch or hard spot: Debris packed in the housing or early bearing failure
  • Wobble or side-to-side play: Bearing play — replace before it gets worse
  • Loud or noisy rotation: Bearing on the way out

Do the same check on every idler pulley and drive pulley on the deck. Idler pulleys often get overlooked — they spin at high RPM and a failed idler bearing will shred a belt instantly. Any pulley that doesn’t spin freely and quietly should be replaced.

💡 Winter Is the Right Time to Replace These

Parts ordered in the off-season ship quickly, prices are stable, and you have time to do the job without a customer waiting for their machine. Replacing a worn spindle in October takes an hour. Replacing it in May when you’re slammed takes the same hour but costs you a customer and a day of lost revenue or lawn care.

04 Blades — Sharpen, Balance, or Stock a Spare Set

Winter is the ideal time to deal with your mower blades. The mowing season is over, there’s no urgency, and a sharp set of balanced blades will be ready to drop straight on the machine come spring.

STEP 1

Remove, Inspect, and Sharpen or Replace

Remove each blade and look at the condition carefully. If the blade is bent, cracked, or heavily nicked, replace it — no amount of sharpening fixes a damaged blade. If it’s just dull, sharpen and balance it. An out-of-balance blade creates vibration that wears spindle bearings over a season, so balancing is not optional.

A simple cone-style blade balancer is a few dollars on Amazon and tells you instantly whether a blade is balanced. A blade that tips to one side needs a little more metal removed from the heavy end before it’s ready to go back on the machine.

STEP 2

Consider Buying a Spare Set

Buying a second set of blades at the end of the season is a habit worth starting. You can rotate sets mid-season without downtime — when the blades on the mower get dull, swap the sharp set on and take the dull ones in to be sharpened at your convenience. If you hit something during the mowing season and bend a blade, you have a replacement on the shelf immediately instead of waiting on a parts order.

Aftermarket blades from Oregon, Rotary, or A&I Products fit most major brands and cost significantly less than OEM. Keep a set on the shelf and you’ll never be down because of a blade.

05 Engine Service — Oil, Filter, and Hydraulics

End of season is an excellent time to service the engine rather than waiting until spring. Used oil contains combustion byproducts and moisture that will continue to corrode internal engine components if left sitting all winter. Fresh oil over the winter is better for the engine than used oil.

STEP 1

Change the Engine Oil and Filter

Warm the engine briefly so the oil flows easily, then drain and replace with fresh oil to the correct specification for your engine. Replace the oil filter at the same time if your engine has one. Consult your owner’s manual for the correct oil type — most air-cooled small engines call for SAE 30 or 10W-30, but Kawasaki, Kohler, and Honda have specific recommendations.

Fresh oil going into storage means you’re starting next season with clean lubricant already in the engine. That’s one less thing to do in the spring when you’re already busy.

STEP 2

Hydraulic System — Service or Check Level

If your machine is due for a hydraulic fluid and filter change based on hours, do it now. Hydraulic fluid degrades over time and with heat cycles — old fluid won’t protect your transmission or wheel motors as well as fresh fluid. Check your owner’s manual for the service interval, which is typically every 200–400 hours depending on the machine.

If you’re not due for a full change, check the hydraulic fluid level when the machine is cold and has not been run. Hydraulic fluid expands significantly when hot — checking it hot will give you a false high reading and you may end up underfilling after a cold-start next spring. Check it cold, top off to the correct level if needed, and note the hours for next season’s service interval.

⚠️ Always Check Hydraulic Fluid Cold

This catches people every season. The dipstick or sight glass on a zero-turn hydrostatic system will read significantly higher when the fluid is hot. If you check it after running the machine and top it off, you’ll have overfilled it. Check the level only on a cold engine — before you start it for the day. Overfilling a hydraulic system can cause foaming, erratic drive response, and seal damage.

06 Tire Pressure — More Important Than Most People Realize

This one gets overlooked almost every time, but it matters more than it seems. Tires lose pressure over a cold winter as temperatures drop — a tire that was properly inflated in October can be noticeably low by March.

More importantly, unequal tire pressure causes an uneven cut. If the drive tires on a zero-turn are at different pressures, one side of the machine sits slightly lower than the other. That difference in deck height is translated directly to the lawn — one side of the deck scalps while the other cuts high. This is one of the most common causes of inconsistent cut quality that homeowners blame on deck level or blade condition, when the real culprit is a few pounds of difference in tire pressure.

STEP 1

Check and Equalize All Four Tires

Check the pressure on all four tires with a quality gauge and inflate to the manufacturer’s specification — typically 10–14 PSI on most zero-turns and riding mowers, but check your owner’s manual for the exact spec. The front and rear may have different target pressures. Set all tires to the correct spec, make sure matching tires (left and right) are equal to each other, and check again before the first mow of spring after any significant temperature change.

07 Final Steps — Clean Up and Store Right

Before you park it for the season, take 15 minutes to clean the underside of the deck if you haven’t already. Packed grass and debris holds moisture against the metal deck surface and accelerates rust. Scrape it out, blow it clean, and if you have a deck coating or rust inhibitor spray, apply a light coat to the underside.

Grease all spindle zerks, wheel bearings, and any other grease fittings on the machine. Fresh grease going into storage displaces any moisture that worked its way into the bearing cavities during the season and keeps everything moving freely when you come back to it in the spring.

Store the machine in a covered, dry location if at all possible. A machine stored outdoors under a tarp will survive, but UV exposure degrades belts and hoses, moisture gets into everything, and rodents have a habit of nesting in the engine compartment and chewing wiring. A garage or shed is always better.

🛒 Products for Winterization

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08 Final Thoughts

Winterizing a mower isn’t complicated — it’s just a series of straightforward tasks that most people put off because the season just ended and the last thing they want to do is more mower work. But every one of these steps pays back more than it costs. A battery that lasts two more years because of a $25 float charger. A carburetor that doesn’t need cleaning because you ran stabilizer through it. A spindle you caught in November instead of April when your schedule is packed.

Print the checklist at the top of this post, work through it once, and park the machine knowing you’ll pull a healthy mower out of storage come spring. That’s a good feeling.

Questions about any of these steps for a specific machine? Drop them in the comments — I’ve seen most of what goes wrong with these machines over 18 years in parts and I’m happy to point you in the right direction.

Related Reading on Mow Maintain and More

While you’re under the deck this fall, it’s the perfect time to check your spindles and belts in detail. Our guide on replacing a zero-turn spindle covers everything from identifying a failing bearing to choosing between OEM and aftermarket housings.