How To Winterize Lawn Mower

Learning how to winterize lawn mower is an essential fall task for any homeowner. Preparing your mower for storage involves a few key steps to protect its engine and components from cold-weather damage. Taking the time to do this properly ensures your machine starts easily and runs smoothly when spring arrives.

Neglecting this process can lead to costly repairs. Stale fuel can gum up the carburetor, moisture can cause rust, and cold temperatures can damage the engine block. By following a systematic approach, you can extend the life of your mower significantly.

This guide will walk you through the entire process, from gathering supplies to the final storage step. Whether you have a push mower or a riding tractor, these principles apply.

The core process of winterizing focuses on protecting the fuel system and engine internals from corrosion and varnish. It also involves cleaning and safeguarding the mower’s exterior. You should aim to complete this task after your last mow of the season, before the first hard frost sets in.

Set aside about an hour for a push mower, and up to two hours for a riding mower. You will need some basic tools and supplies, most of which you probably already have in your garage.

Gather Your Supplies

Before you begin, collect all necessary items. This makes the job faster and prevents you from having to stop halfway through. Here is a basic list to get you started:

Fresh fuel (or a fuel stabilizer)
A fuel container for syphoning
A socket set or wrenches
New spark plug
New air filter
Engine oil and a drain pan
Stiff brush and scraper
Garden hose (optional for cleaning)
Cloths or rags
Protective gloves and safety glasses

Safety First: Preparation Steps

Always prioritize safety when working with machinery. Start by disconnecting the spark plug wire on a push mower. For a riding mower, remove the key from the ignition. This prevents the engine from accidentally starting while you are working on it.

Allow the mower to cool completely if you have just used it. Working on a hot engine can lead to burns, and hot components can be a fire hazard when dealing with fuel. Ensure you are in a well-ventilated area, preferably a garage with the door open.

Disconnect the Battery (For Riding Mowers)

If you have a riding mower with a battery, disconnect it. First, remove the negative (black) cable, then the positive (red) cable. This prevents any slow drain over the winter. Some experts recommend removing the battery entirely and storing it indoors on a wooden block, keeping it on a trickle charger.

Step 1: Drain Or Stabilize The Fuel

This is the most critical step in the entire process. Old gasoline left in the tank and carburetor will evaporate and leave behind a sticky residue called varnish. This clogs the tiny jets and passages in the carburetor, leading to starting problems.

You have two main options: draining the system completely or using a fuel stabilizer.

Option A: Using Fuel Stabilizer

This is the easier method for most people. Add a high-quality fuel stabilizer to a nearly full gas tank. Run the engine for 5-10 minutes to circulate the treated fuel throughout the entire system, including the carburetor. This stabilizes the fuel for up to 12 months, preventing degradation.

Option B: Draining the Fuel System

For long-term storage or if you prefer not to use stabilizer, you can drain the system. First, siphon or pump the gasoline out of the fuel tank into an approved container. Then, to drain the carburetor, locate the carburetor bowl (usually a small, bulb-shaped component at the bottom of the carburetor). Place your drain pan underneath and loosen the drain screw to let the fuel run out. Run the engine until it stalls to use up any remaining fuel in the lines.

Step 2: Change The Engine Oil

Never store a mower with old, used oil. Contaminants in the oil become acidic over time and can corrode internal engine parts during the months of inactivity. Change the oil while the engine is warm, as it flows out more easily.

Locate the oil drain plug on the bottom of the engine or use the dipstick tube if your mower has a suction system.
Place your drain pan underneath and remove the plug or dipstick.
Let the oil drain completely.
Replace the drain plug and refill with the type and amount of oil recommended in your owner’s manual.

Step 3: Replace The Air Filter And Spark Plug

A fresh air filter ensures clean air intake, and a new spark plug provides a strong ignition source for spring. These are inexpensive parts that make a big difference.

To change the air filter, simply remove the cover, take out the old filter, and insert the new one. If you have a foam filter, you can clean it with warm soapy water, let it dry, and apply a few drops of fresh engine oil before reinstalling.

For the spark plug, use a spark plug socket to remove the old one. Check the gap on the new plug with a gap tool, adjusting if necessary to match your manual’s specification. Then, thread it in by hand to avoid cross-threading before tightening with the socket.

Step 4: Clean The Mower Deck And Blades

Grass clippings and moisture under the deck create a perfect environment for rust. A thorough cleaning prevents this and keeps your mower balanced.

Tip the mower on its side (with the air filter and carburetor facing up to prevent oil leakage).
Use a putty knife or stiff brush to scrape away all caked-on grass and debris.
You can use a hose to rinse the deck, but be careful not to directly spray the engine, air filter, or electrical components. Allow it to dry completely.
Inspect the blade for nicks and damage. Sharpen or replace it if needed. A sharp blade makes for a healthier lawn next year.

Step 5: Lubricate Moving Parts

Apply a light machine oil or silicone spray to the mower’s moving parts to prevent rust and keep them operating smoothly. Key areas to lubricate include:

The throttle and choke linkages
The wheel axles (if they are not sealed)
The height adjustment levers
The cable controls on a riding mower

Avoid using heavy grease, as it can attract more dirt and dust during storage.

Step 6: Choose The Right Storage Location

Where you store your mower is just as important as how you prepare it. The ideal location is clean, dry, and protected from the elements.

A garage or shed is perfect. If you must store it under a tarp outdoors, ensure the tarp is breathable to prevent condensation from building up underneath, which leads to rust. Make sure the storage area is free from rodents, who might chew on wiring or make a nest inside the mower deck.

Special Considerations For Riding Mowers

Winterizing a riding lawn mower follows the same core steps but with a few additions. Beyond disconnecting the battery as mentioned, you should also:

Check and inflate the tires to the proper PSI to prevent flat spots.
Consider adding a fuel stabilizer with a higher dose due to the larger fuel tank.
Clean the battery terminals with a wire brush before storage.
If your model has a battery, store it indoors on a trickle charger.

Common Mistakes To Avoid

Even with good intentions, it’s easy to make errors that can harm your mower. Here are the most frequent mistakes people make:

Leaving old fuel in the tank all winter. This is the number one cause of spring starting failures.
Forgetting to disconnect the spark plug wire, leading to a safety hazard.
Storing the mower with a dirty, wet deck which accelerates rust.
Neglecting to change the oil, allowing contaminants to sit in the engine.
Using the wrong type of oil when doing the change.

Spring Start-Up Checklist

When the grass starts growing again, you’ll be glad you winterized properly. Here’s a quick list to get your mower ready for its first cut:

Reconnect the spark plug wire or install the battery (fully charged).
Check the oil level and top up if necessary.
If you drained the fuel, fill the tank with fresh gasoline.
Check the tire pressure on riding mowers.
Give the mower a quick visual inspection for any issues.
Start the engine in a clear area and let it run for a few minutes.

Frequently Asked Questions

Here are answers to some common questions about winterizing lawn mowers.

Is It Better To Drain Gas Or Use Stabilizer?

For most homeowners, using a fuel stabilizer is simpler and just as effective. It’s the recommended method for modern ethanol-blended fuels. Draining is a good option if you are storing the mower for more than a year or if you are comfortable with the extra steps.

Can I Just Run The Mower Until It’s Out Of Gas?

Running the tank dry is not sufficient. While it empties the tank, it does not remove fuel from the carburetor bowl and fuel lines, where it can still evaporate and leave residue. You need to either treat the fuel or physically drain the carburetor.

Do I Need To Change The Oil Every Year Before Storage?

Yes, it is highly recommended. Old oil contains combustion byproducts and moisture that can corrode engine bearings and other internal parts during long periods of inactivity. Fresh oil provides a protective coating.

Where Should I Store My Lawn Mower For The Winter?

A clean, dry, and cool place like a garage or shed is ideal. Avoid damp basements or outdoor storage without a proper, breathable cover, as consistent moisture is the enemy of metal components.

What If I Forgot To Winterize My Mower?

If you discover this in the spring, you will likely need to drain all the old fuel and replace it with fresh gas. You may also need to clean or rebuild the carburetor if the mower won’t start. It’s still a good idea to change the oil and check the spark plug before attempting to use it.

Taking the time to properly winterize your lawn mower is an investment in its longevity and your peace of mind. By following these steps, you protect your equipment from preventable damage and ensure it’s ready for reliable service when you need it most. A little effort in the fall saves you time, money, and frustration next spring.