How to Winterize a Zero Turn Lawn Mower: Step-By-Step

It’s tempting to shove your zero-turn into the corner after the last cut of the season and forget about it. You may even plan to winterize the mower, but before you know it, it’s time to mow again.

When you don’t prepare your mower for winter storage, you can run into starting and running issues when you go to use it in the spring.

Winterize a zero-turn lawn mower by emptying the fuel tank or stabilizing the fuel to remove moisture and prevent gasoline from breaking down; remove the battery or charge it so it does not freeze, and remove debris and grease the zero-turn to prevent corrosion.

Don’t compromise your investment by not preparing your zero-turn for storage.

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing, or operating.Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Checklist to Prepare Your Zero Turn Mower for Winter

This list includes everything to service your zero-turn and prepare it for winter storage.

• Gather tools and supplies
• Check the safety systems
• Remove dirt and debris from the exhaust, engine, and hydraulic systems
• Change engine oil and filter
• Clean or replace the air filter
• Check hydraulic oil. Change hydraulic oil and filter if necessary.
• Replace spark plug
• Replace the fuel filter and inspect the fuel lines
• Check tire pressures & lug nuts
• Check the condition of belts and pulleys
• Sharpen or change mower blades
• Scrape the deck
• Wash and dry your mower
• Drain the fuel tank or add a fuel stabilizer
• Charge or remove the battery
• Lubricate the zero-turn and mower deck
• Add dielectric grease to terminals and connections
• Add a rodent deterrent

Winterize Your Zero Turn Lawn Mower: Step-By-Step

Step 1: Collect Tools & Supplies

It is best to get all of the materials together before you start servicing your zero-turn.

• Engine Oil and Filter
• Hydraulic Oil and Filter, if needed
• Air Filter
• Fuel Filter
• Spark Plugs
• Socket or Spanner Wrenches
• Drain Pan, Funnel, Filter Wrench
• Fuel Stabilizer (Sea Foam)
• Rags, Work Gloves, Safety Glasses, Work Surface Cover
• Deck Scraper, Wire Brush, or Metal Putty Knife

Step 2: Check the Zero Turn Safety Systems

A zero-turn mower has a safety system to reduce injury when operating it. There are safety switches that prevent the engine from starting when the parking brake is not engaged and the levers are not in the open/outward position.

The engine should also shut down if your PTO is engaged and the operator leaves the seat.

There are other safety switches included on your zero-turn that you will need to confirm are in working condition. Refer to the operator’s manual to review all safety features of the zero-turn’s interlock system to ensure the safety features are reacting like they are designed to.

In addition to these safety features, inspect the rollover protection system (ROPS) and seat belt to make sure they are in good working order and have not been compromised. For your safety, the ROPS and seatbelt are designed to work together.

Zero-turn lawn mowers are dangerous. Keeping the safety system in good working order can reduce these dangers along with operating the mower safely avoiding water features and steep hills.

Read the “Dangers of Zero Turn Mower & How to Operate Safely” for tips on operating your zero-turn safely.

Step 3: Remove Dirt and Debris from Exhaust, Engine and Hydraulic Systems

Remove any obstructions that are preventing air from flowing around the engine and exhaust areas. When air isn’t able to circulate around the engine block, the engine can overheat.

Remove the engine shroud. Remove dirt and debris from the engine and exhaust areas. Check the cooling fins. Remove dirt that has built up in the fins and repair any fins that are broken. Make sure the heat shield is securely in place.

Continue cleaning around the hydro fan cooling fins, guards and fan to keep the transmission cool.

Step 4: Change Engine Oil and Filter on Zero Turn Mower

Change your engine oil and filter annually or sooner if you are using it more than the average homeowner. Refer to your operator’s manual for the hourly oil change interval as this can vary by engine model.

Not changing your engine oil regularly can have damaging effects to the engine. Note: If your engine is new, you need to change the oil after the initial 5-10 hours.

Prepare Work Surface: Lay covering over your work surface to prevent oil spills from penetrating the ground. Cardboard and newspaper work well.

Warm Engine Oil: Start your zero-turn, park it on top of the work surface cover, and let it run for 2 to 3 minutes to warm the engine oil. Warm oil flows better than cool oil.

Take caution when working around the hot engine. You don’t want your oil to be hot as this could cause burns while working with it.

Remove the Key & Unplug the Spark Plug Boot: Remove the ignition key and spark plug boot(s) to keep your mower from starting while servicing your zero-turn. This is a necessary safety precaution to prevent serious injury.

Remove Engine Oil Plug: Clean dirt and debris from the area around the oil plug so you don’t contaminate the engine when removing the oil plug. Place a drain pan under the oil plug, remove the plug and allow the oil to drain into the pan.

Some zero-turn engines use an oil hose port in place of a drain plug.

Replace Engine Oil Filter & Oil Plug: Using a filter wrench, remove the oil filter and replace it with a new filter. Place a light film of fresh oil on the gasket of the new filter and place it on the engine. Once all of the oil has drained, reinstall the drain plug.

Fill with Engine Oil: Fill the crankcase with the quantity and type of engine oil recommended by your manufacturer. You must make sure you have a sufficient engine oil level. It cannot be too low or too high as either level can cause damage.

Start Engine and Check Oil Level: Reinstall the spark plug boots and start your engine for a few minutes. Turn the engine off and let the oil cool. Recheck the oil fluid level. Add more oil if needed.

Disconnect the spark plug boot while you continue to work on your lawn mower. Only connect it when needing to start your mower while you take the necessary safety precautions. You don’t want your mower to start when you least expect it.

Step 5: Replace or Clean Your Zero Turn’s Air Filter

I recommend changing your air filter annually. The engine requires clean air to run. Because of the dusty conditions that come from operating a zero turn, the air filter can become plugged restricting airflow if it is not replaced or cleaned regularly.

Restricted airflow will cause your mower to run sluggishly and feel like it’s losing power because it isn’t getting enough air. Replace your air filter annually and clean it several times throughout the mowing season.

Steps to clean a paper zero-turn air filter:

• Remove the air filter cover from the housing.
• Carefully remove the filter to prevent dirt from falling into the air intake.
• Wipe out any dirt that remains in the air filter housing with a dry clean cloth.
• Tap the air filter against a hard surface to knock the dirt loose so it falls out of the filter.
• Hold the filter up to a light source, or use a flashlight, to check for light shining through the paper filter.
  • If you don’t see light or the filter is damaged or covered in oil, do not reuse the filter. Purchase a new air filter.
  • If you do see light and the filter is in good condition, go ahead and reuse the filter.
• Install the new or cleaned air filter and reattach the air filter cover.

Check out “Guide to Lawn Mower Air Filters: Differences & How to Clean Them” for information on cleaning other types of air filters.

Step 6: Change Hydraulic Oil and Filter if Necessary in Your Zero Turn

Operating your zero-turn with low or old hydraulic fluid can cause your mower to seem weak when moving. It can also cause extensive damage to the transmission. Change your hydraulic fluid and filters at the interval recommended by your manufacturer.

Keep in mind, most manufacturers have an initial break-in period where the oil needs to be changed sooner than the standard interval. Some initial break-in periods are as soon as 75 hours.

Some entry-level zero turns have unserviceable hydraulic systems that don’t allow you to change the hydraulic oil.

Refer to your manual for the correct procedures for changing your hydraulic oil as it can vary with each model. Air must be removed from the system after an oil change. For most mowers, raise the rear tires off of the ground.

Here are the most common directions for changing your hydraulic oil on a zero turn:

Park Zero Turn on Flat Surface: Remove the key and engage the parking brake. Wait for all moving parts to stop before working on your zero-turn. Note the engine and transmission can be hot. Take caution when working. 

Locate Filters & Remove Guards: You will find the filter located near each rear wheel. There may be a guard or skid plate over the filter. Remove the guard and clean around the filters before removing them. 

Don’t skip cleaning around the filters. You do not want to introduce any dirt or other foreign materials into the hydraulic system. 

Remove Filters & Drain: Place an oil pan under one of the hydraulic filters. Unscrew the filter and let the oil drain. Repeat with the other hydraulic filter. Remove the drain pan and plan on bringing the old oil to your closest recycling center.

Install New Filters: Apply a thin layer of fresh hydro oil on the rubber seal of the new filters. Install the filters by turning clockwise. Once the filter makes a good connection to the filter adapter continues to turn about another full turn. 

Fill with Recommended Hydraulic Oil: Fill with fresh hydraulic oil through the expansion reservoir. The expansion reservoir is the little small plastic tank on the top of your mower behind the seat.

Clean around this area before you remove the cap. Fill until it is at the “full cold” line on the tank. You may have two tanks, one on each side of the mower.

Some transaxles will have a vent plug located on each transaxle. Loosen this plug on each side. You will fill the hydro oil through the expansion reservoir until oil comes out of the vent plug.

Tighten the vent plugs and continue filling until the oil level reaches the “cold full” line on the expansion reservoir.

Purge Air Out of the Hydraulic System: It’s important to get all the air out of the system by going through some steps with the drive tires turning freely.

In order to allow the drive wheels to turn freely, you will need to get the rear wheels off the ground. Do this by using jack stands to raise the rear of the mower just high enough so the wheels no longer touch the ground. 

Start your mower and increase the throttle to about ½ throttle. Release the parking brake. Move the speed levers forward and reverse several times for a few minutes total until your wheels begin to rotate at a normal rate and with a normal sound.

Let the hydraulic system cool and re-check your oil level. Add more oil if needed.

Step 7: Replace Your Zero Turn Mower Spark Plug(s)

Replace your spark plug(s). A spark plug can become dirty and cause intermittent spark issues which result in starting and running issues. I prefer to change them out annually. It is a pretty inexpensive item to replace so you don’t have to worry about the spark plug during the mowing season.

Make sure your spark plug is gapped to the specification provided by the engine manufacturer. Don’t attach the spark plug wire (boot) until your mower service is complete.

Step 8: Replace Fuel Filter & Inspect Fuel Lines on Your Zero Turn Mower

Dirty fuel and ethanol in fuel can break down and be corrosive to the fuel system and clog your fuel filter and fuel lines. Replace the fuel filter and inspect the fuel lines. Fuel lines need to be replaced when they become dry and brittle.

Make sure the arrow on the side of the fuel filter is installed so it is pointed in the direction of your mower’s fuel flow.

Step 9: Check Your Zero Turn Tire Pressures & Lug Nuts

Make sure your lug nuts are tight and your drive tire pressures are equal on each side. They should be filled to the pressure recommended by your zero-turn manufacturer.

Uneven tire pressures can cause uneven cutting conditions. It can also cause your mower to pull one way causing your mower not to move in a straight path.

Step 10: Check Condition of Your Zero Turn Belts, Pulleys & Spindle Housings

When servicing your zero-turn, the belts and pulleys must be inspected. Worn belts and pulleys can cause your hydraulic pump or mower blades not to work properly. If your belts appear worn, cracked or have a glazed appearance to them, you need to replace them.

Over time, bearings can wear and become damaged. To check the bearings in your pulleys, you will want to slowly turn each pulley to ensure they are still moving freely and you don’t feel any resistance.

While turning the pulley, listen for any noise coming from your bearing. Replace the pulley if you hear noise, feel resistance, or don’t sit level (wobble).

Check for bearing wear in your spindle housing. Do this by grabbing a hold of each side of the mower blade while wearing a good pair of work gloves to protect your hands from sharp edges.

Rock the blade with an up-and-down motion. If you feel movement, you need to replace the bearing or spindle housing assembly.

Note: Some manufacturers only allow you to rebuild a spindle housing, some only sell the spindle housing assembly while others offer both.

Step 11: Sharpen or Change Your Zero Turn Mower Blades

Dull blades will put extra strain on your zero-turn engine in addition to giving you a poor cut.  You may have noticed times when your lawn looks unhealthy with brown ends a couple of days after mowing. This is likely due to operating your zero turn with dull blades.

Not having sharp blades will beat up the grass instead of precisely cutting the grass. Each time you service the zero-turn mower you need to inspect your mower blades to determine whether they should be sharpened or replaced.

If you find a blade that is damaged or bent you must replace your mower blades.

Read more about inspecting your mower blades and the different ways to sharpen your blade with my article “How to Change and Sharpen Your Zero Turn Mower Blades”.

Step 12: Scrape Your Zero Turns Mower Deck

Gain access to the underside of your zero-turn mower deck by using jack stands or one of these handy lifts from Amazon. Keeping the mower deck clean will provide you with a better cut and better mower performance.

Buildup underneath the deck compromises the air movement needed to create a good cut. The mower blade is designed to create air movement in the deck.

The blade along with the suction created in the mower deck makes the grass blade stand tall so the blade can pass by and precisely cut the grass blade.

Scrape the deck using a deck scraper or metal putty knife each time you service your zero-turn mower deck. A good stiff wire brush also works well.

Step 13: Wash and Dry the Zero Turn Mower

Use a garden hose to wash your zero-turn mower to remove dirt and debris stuck to the mower. If using a pressure washer, do not use a high pressure to wash your mower as sealed components can be damaged.

Allow the mower to completely dry before storing. Any moisture left in your mower can corrode the mower and cause problems to the electrical system.

Leaving the mower to dry outside on a nice sunny day will help evaporate the moisture. Using a leaf blower can help speed up the process.

Once your mower has been serviced, washed, and completely dry, move your mower to the location you will be storing it for winter if you choose to remove the battery and/or empty the fuel tank for storage before completing the following steps.

Step 14: Drain the Fuel Tank or Add a Fuel Stabilizer to the Fuel

When storing your mower for winter, you don’t want to let fuel sit in your mower without emptying the fuel tank or stabilizing the gas. Gasoline will begin to break down as soon as 30 days after you buy it.

Ethanol, found in most gasoline, attracts moisture that is not only corrosive to the fuel system, but it can also leave behind sticky deposits that can clog the fuel system. This residue is worsened if left sitting for long periods like during the winter season.

You have the option of draining the fuel tank or adding a fuel stabilizer to the fuel before storing it. If you choose to drain it, use a fuel siphon pump to remove fuel from the fuel tank. Start the mower and allow it to run until it shuts off due to lack of gas.

I choose to add Sea Foam Motor Treatment to my zero-turn mower before I place it into storage. Sea Foam stabilizes the gas, reduces moisture, and cleans the fuel system. Find more information on the benefits of using Sea Foam in a lawn mower here.

How to Use Sea Foam in Lawn Mowers

A 16-ounce can of Sea Foam treats up to 16 gallons of fuel. Follow these instructions to add Sea Foam to your gas.

1. Fill a 1-gallon gas can with 1-gallon of gas. 
2. Then add the appropriate amount of cleaner to the can.
   • 1 ounce for every gallon when used as regular fuel maintenance.
   • 2 ounces for every gallon when cleaning your fuel tank. Using more than 2 ounces is okay. The more you use, the better the solution cleans.
3. Add fuel to the fuel tank.
4. Start the zero turn and allow it to run to work the treated gas through the fuel system.

Step 15: Remove or Fully Charge the Zero Turn Battery

When storing your mower in cold conditions, you must either remove your battery or fully charge the battery so it won’t freeze. If you choose to remove the battery, store it in a dry area where it won’t freeze. Keep it away from damp and humid areas.

You can read more about this in an in-depth article on battery care over the winter in, “A Guide to Winter Lawn Mower Battery Care“.

A fully charged battery won’t freeze. Most zero-turn batteries are 12-volt batteries. Check your battery voltage using a voltmeter. If your battery reading is 12.6 volts or greater your battery is 100% charged. When the voltage reading is less than this, you need to charge your battery.

Make sure all cables are tight. Clean or replace the terminals if they are corroded.

Charge Your Zero Turn Battery

• Disconnect the battery cables from the battery. Remember: Positive cable (Red +) is the last one off and the first one on. Now, if the battery has removable caps check the water level. If the plates inside the battery are not covered with water you will need to add distilled water to them. Note: well water is not good for a battery. City water is a little better option, but it is best to use distilled water for your battery.
• After checking the water level, hook the charger to the battery.
• Check the battery voltage with your meter and see what it has in it. If the battery has 11.8 volts in it you won’t have to charge it very long. If it has 10.1 volts your battery is going to need to sit on a charger for a while. The lower the voltage reading, the longer your battery will need to sit on the charger.

  I like to put a very low battery on what is called a “slow bake”. Some battery chargers have different switches on them such as 6 amps, 4 amps, or 2 amps. Charge a very low battery on 2 or 4 amps and let it charge for about an hour. After an hour, check the reading to make sure the voltage rate is increasing. If it is, continue to charge for another hour.

Step 16: Add Dielectric Grease to the Zero Turn Terminals and Connections

Clean your battery terminals and make sure the cables are in good condition and securely in place. Use a baking soda mixture (2 cups of water and 3 heaping tablespoons of baking soda) and a wire brush to remove corrosion from the terminals.

Add a thin layer of dielectric grease to the terminals and electrical components to prevent corrosion.

Step 17: Lubricate the Zero Turn and Mower Deck

Using a high-performance high-temperature grease, lubricate the idler arm pivots on the deck and pumps and all other pivot points and grease zerks on your zero turn. Refer to your operator’s manual to verify all grease points on your mower.

Some caster wheels will also need to be greased. Wipe off excess grease.

Lubricate the cables using a product like WD-40 or Sea Foam Deep Creep to prevent the cables from freezing up and corroding.

Step 18: Add a Rodent Deterrent to Protect the Zero Turn

Over my years of working with lawn mowers, I have seen many mowers where mice have built nests under the hood and chewed through the wire harness while the mower was in storage over winter.

Using a product like Grandpa Gus’s Mouse Repellent will help deter mice and save you from a large repair bill. It comes in both packets to place around your mower and a spray that can be used on the wiring.