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Lawn Mower Winter Storage – Mechanics top tips

By: Author John Cunningham. Published: 2019/02/10 at 6:41 pm

Simple prep work now will save a lot of headaches later. It’s very important to clean old grass and debris from your mower. As grass decomposes, it produces acid, which eats away at the metal components of your mower.

So what is lawn mower winter storage? Mower winter storage is the practice of prepping the engine and body so that they are protected from the environment. The six basic steps to successful winter lawn mower storage include:

  1. Clean the mower
  2. Treat the gas with stabilizer
  3. Treat the engine cylinder
  4. Charge battery (tractor)
  5. Add body coating
  6. Store the mower indoors

Most of the mowers that reach my workshop in the spring have problems associated with poor or no winter storage preparation.
If you take care to winterize your kit, you’ll have trouble-free recommissioning in the spring. Winter storage is a chore many owners skip, and come spring, they pay the price.

Getting small engine equipment winter prepped isn’t difficult, and if you need a little more help, check out the “Mower winterizing video” it walks you through the process step by step – cleaning, cylinder protection, gas system preparation, and body protection.

Walk-behind mower or lawn tractor, the process is much similar. However, before working on a walk-behind mower, it’s best to disable your engine to prevent accidental starting.

The process is as follows:

Disable Mower Engine

Plug wire off

Remove – Remove the plug lead and turn off the gas to disable the mower.

Gas Off – Turn off-gas. Not all mowers have a gas valve. To help locate your fuel valve, check out “Fuel valve location”

Gas tap

Tools You’ll Need

You don’t need much in the way of tools:

  • Stiff brush
  • Paint scraper
  • Plug spanner
  • Small amount of engine oil
  • WD40 (1 can)
  • Tire pump (tractor)
  • Battery charger (tractor)
  • Adjustable wrench
  • Power washer (ideally)

1 Mower Cleaning

This is the dirty part: scraping and brushing to remove all the dry grass that would happily eat your mower over the winter months. Begin by removing any large clumps of grass and using soapy water; wash the surface area of your mower deck, engine, wheels, etc.

I prefer not to use a garden hose or pressure washer, if possible, as it forces water into cables and electrics, causing problems later.

Turning Mower Over

Turn mower over

With the top side clean, it’s time to turn your mower over, but there’s a wrong and a right side.

A mower should always be turned over with the air filter side facing upwards. If you need video help, you’ll find it here.

Deck Cleaning

If your mower is a riding mower, place a block under the front wheels and apply the brakes. This gives you enough room to reach under and clean the deck.

A paint scraper and stiff brush work best.

Deck clean port

Both walk-behind and lawn tractor mower decks are equipped with a useful garden hose connector on the deck.

After you’ve cleaned the heavy grass, turn your mower over (plug wire and gas back on), connect your water hose, and run the engine and blades to thoroughly clean the underside.

It makes a bit of a mess, so be prepared and execute this step on the lawn.

Now run the engine with the water off, allow the engine to heat up, and spin the blades to drive off the excess water. When done, wipe down the mower, drying off any remaining water.
Allow the mower to dry out completely (you may need to come back to this step later). Turn the mower over once more, and spray the underside of the deck with WD40; this will protect against rust and dampness over the winter months. Take care not to spray any belts or pulleys directly.

Deck rust

Corrosion – Sadly, this garden hose connector wasn’t overworked.

Jacking – Use a car jack to lift the front of your mower, and place blocks of wood under the front wheels. Apply the brake and leave the jack under the mower for additional support.

Often, finding somewhere to jack the mower can be a challenge; be careful of steering arms and the muffler. Alternatively, drive your mower onto a high curb.


Deck Cleaning – With the deck in the highest position, it’s not going to be comfortable, but it’s enough clearance to get the job done.


Grass Bag/box – It’s important to wash the grass bag or box. Matted grass blocks air from passing through the bag, and this, in turn, stops grass filling.

A pressure washer is the best way to clean the bag; otherwise, use a stiff brush and some soapy water. Allow the bag to dry completely before storing it for winter.

2 Treating The Gas

Bad gas is the number one reason for a lawnmower no-start. Gas goes stale and blocks up the gas system. How long gas stays fresh depends on factors such as the temperature stored, where it’s stored, how full the gas tank/can is, and the type of gas.
All mowers are affected, even new ones. Manufacturers won’t cover stale gas under your warranty. In lots of cases, cleaning will fix the problem, but some will need a new carburetor fitted, which is expensive!

The easiest way to avoid problems with gas is to add a fuel stabilizer. This is as easy as emptying a few drops of fluid into the fuel tank and operating the engine for a short time to mix it throughout the fuel system. 

The gas stabilizer will keep your fuel fresh all winter; it will also work in another gas-powered kit, 2-stroke or 4. You can put it into your gas storage can also.

If you don’t want to use a fuel stabilizer, then simply drain the gas tank and run the engine until it stops. This isn’t as good as the stabilizer, as a residue may remain in the system. All is going well; adding some fresh gas in the spring, and you’re ready to mow.

Regular gas is best for your small engine; ethanol E10 is fine, but E15 is not; it will damage your engine as this fuel burns hotter. All ethanol fuels attract moisture, and moisture corrodes the fuel system.

Bowl corrosion

If you forget to drain the gas – cleaning will sometimes fix the problem, but if the corrosion is too bad, you’ll need to replace the whole carburetor.

I wrote a complete guide on “Carburetor cleaning”

At the end of the season, don’t forget to empty and clean your gas can; often, it’s the cause of gas system contamination.

Draining – Draining out the gas at the end of the season will help prevent the gumming of the gas system.

Tank drain

Stabilizer – But this is the guaranteed fix. Add some stabilizer to the gas tank and run the engine for 10 minutes – job done!

3 Treating The Cylinder

Most manufacturers recommend removing the spark plug and pouring a cap full of engine oil into the cylinder. Turning (cranking) the engine over by hand coats the cylinder with oil; this prevents any moisture from turning into corrosion over the winter months.

Refitting the spark plug and turning over the engine by hand until resistance is felt closes the valves, further helping to prevent dampness. 

Here’s the process for both tractor and walk-behind mowers.

Lawn Tractor

Protecting the cylinder is a simple two-step process, as follows:

Oil cylinder

1 – Remove your tractor mower spark plug and allow a cap full of oil to drain in.

2 – Crank over the engine to coat the cylinder, refit the plug, but not the plug wire, crank over the engine by hand (if you have access) until you feel resistance.

The valves are now closed.


Walk Behind

Protecting the cylinder is a simple two-step process, as follows:

Oil cylinder

1 – Remove your spark plug and pour a cap full of engine oil in.

2 – Crank over the engine; now fit the plug without the plug wire, and crank over the engine until you feel resistance. The valves are now closed.

Pull over mower

4 Charge Battery

If you have a key start walk behind a mower or lawn tractor, you’ll have a battery, so we’ll need to prep it for winter. The battery needs some special attention; batteries don’t like to be totally discharged, and it will often kill them. Most mower batteries fail over the winter months because temperatures drop, and the voltage is allowed to drain away until totally flat.
The best solution is to store the battery somewhere warm, but we’ll need to use a battery charger to keep it in top condition. Batteries work best and last longer when their state of charge is maintained, so off-season charging is always advised.

I treated my own tractor mower last year to a new smart charger; I bought the Noco Genius smart charger; check it out on the “Small engine repair tools page.” I’m very happy with it so far; it’s simple to use and works on all battery types.

5 Add Body Coating

You won’t hurt your mower by spraying it with WD, it’s great at keeping dampness out of electrics. Spray down the center of the throttle and drive cables using the straw, stopping cables from seizing over the winter. Coat the whole mower, engine, body, deck, wheels, and handlebars; you get the idea.

The only areas to avoid are belts and pulleys. You may use a whole can, but it’s worth it.

6 Storing Your Mower

A mower should always be kept indoors; mowers that live outside have short lives. Electrical systems fail prematurely, and body corrosion is accelerated. I understand for some, they have no choice. If so, make sure the gas is drained, and the body is clean and dry; if you have a battery, remove it and take it indoors. Don’t forget to coat the body with WD, that will help keep the dampness out.


No Garage – Storing your mower outdoors is not advisable. It will shorten the life of the mower and cost you lots in repair bills. If you don’t have a garage, then drain the gas and cover it with a breathable cover.

A plastic cover will cause condensation to build upon the mower and cause even more damage. Check out “Can riding mower get wet?”.

Indoors – This is the life! It’s even better if the garage is heated. Add a dust cover; now you’re really spoiling her.

Mower indoors

Winterizing A Lawn Tractor Is A Little Extra Work

Riding mowers and lawn tractors is a little extra work; all of the above still applies, but in addition, the tires need to be pumped, and ideally, the chassis should be resting on blocks. This takes the weight off the tires and prevents flat spot damage. And if that sounds like a lot of work, simply park the mower on a heavy rubber mat.

Spray the whole mower with WD40, engine, body, and wheels. Cover down using a breathable cover; a plastic sheet will cause condensation – The Enemy.

When To Tune-up The Engine?

Lots of my customers ask me, “When should I get my mower serviced?”  The spring makes the most sense; machinery dislikes being idle. Lawn equipment will often start right up in the spring after the winter storage, but then stall and refuse to run. Check out the “Mower tune-up guide” here or check out the video here.

Related Questions

Can I store my lawnmower outside in the winter? A mower is best stored indoors; moisture will damage mower components. If a mower can’t be stored indoors, spray the mower engine and body with WD40 before covering it with a good quality, breathable, all-weather cover.
Can you store a lawnmower in the house? Storing your mower in the house is dangerous; gas and oil are combustible and emit vapors that are harmful to both humans and pets.