The residential customers I have worked with seem comfortable changing their own engine oil and filter, but when you mention hydraulics, they seem unsure about the process. 

Many of them end up taking their Exmark mowers into the dealership to have a hydro service performed. If you can change your own engine oil, you most likely will be able to change your own hydraulic oil and filter. 

Change your Exmark Hydraulic Oil and Filter by gathering your supplies and tools, removing the hydraulic filters, draining the hydraulic oil, installing new filters, filling with fresh hydraulic fluid, and removing air out of the hydraulic system.

The advantage of having your local Exmark dealer change your hydraulic fluids is they can check over your Exmark and make sure your mower is in good condition.

Dealerships will check your starting system, safety switches, charging system, belts, pulleys, and more. Just make sure you let them know you want your mower checked over when you schedule your next maintenance. 

Keep reading and I’ll explain what products you need and how to change the oil in your hydraulic system. 

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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.

Exmark Zero Turn Hydrostatic Ground Drive Systems 

The hydrostatic transmissions used in Exmark zero turns vary by model. Here is a chart of the transmissions used in current zero-turn models. 

Type of Hydraulic Oil to Use in Your Exmark  

Exmark recommends you use its Exmark Premium Hydro Oil. Mobil 1 15W-50 oil can also be used in place of Exmark’s oil, however, when using Mobil 1 you must change your oil more frequently. 

Although Exmark’s oil is a little pricier than Mobil 1, it is well worth the extra money especially when you factor in replacing hydraulic filters and spending the time to change your hydraulic fluid twice as often. 

When Exmark recommends changing your hydraulic oil every 500 hours, you must replace it every 250 hours if you choose to use Mobil 1 15W-50. 

Intervals the Hydraulic Oil and Filter Need to Be Changed 

Exmark recommends your first hydro oil change be done after an initial break-in period. This break-in period varies according to Exmark model. Refer to the chart below.

Exmark recommends using Exmark Hydro Oil for most models. Lazer Z models with the Yanmar diesel engine use the Ruby Tran Fluid. Z-Spray models use 5W-40 synthetic oil for their hydraulic system. 

Mobil 1 15W-50 can be used in place of the Exmark Premium Hydraulic Oil for Exmark mowers (except Yanmar diesel models); however, the oil must be replaced more frequently at 250 hours. 

The Quest E-Series & some S-Series models have hydraulic systems that are non-serviceable. What this means is the system is sealed and you are unable to change the hydraulics. If you experience any problems with your sealed system, contact your local Exmark dealer.

Changing Hydraulic Oil in Your Exmark Radius or Exmark Lazer Lawn Mowers 

You will only be changing the hydraulic oil that is drained from the filter. You will never change oil in the whole hydraulic system unless the oil has been contaminated or become very hot. Changing the oil in the whole hydraulic system can cause contaminants to enter the system and cause damage. 

Steps to Change Exmark Radius Zero Turn Hydraulic Oil 

Step 1: Park Exmark on a Flat Surface 

Park your Exmark zero turn on a flat surface. You may want to place cardboard on the ground to keep the spilled oil from penetrating the ground surface before parking your lawn mower on top of it. 

Remove the key and engage the parking brake. Wait for all moving parts to stop before working on your Exmark. Note the engine and transmission can be hot. Take caution when working. 

Step 2: Locate Filters & Remove Guards 

You will find the filter located near each rear wheel behind a guard (skid plate). Remove the guards 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. 

Step 3: 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.

Step 4: Install New Filters 

Apply a thin layer of 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 and continue to turn about another full turn. 

Step 5: Loosen Vent Plug & Fill with Exmark Hydro Oil 

You will find 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.

Once you see oil coming out of the plugs, tighten the vent plugs. The expansion reservoir is the little small plastic tank on the top of your mower behind the seat.

Once the plugs are tightened, keep adding oil until it reaches the “full cold” line shown on the expansion reservoir. 

Step 6: 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 let the Exmark drive wheels 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 wheel no longer touches the ground. 

Start your mower and increase the throttle to about ½ throttle. Release the parking brake. 

• Make sure the bypass valve is open and slowly move the levers both forward and reverse about 6 times. 
• Close the bypass valve and repeat the same procedure moving the levers both forward and reverse about 6 times.  
• Check the oil level with the mower in the off position and once the hydros have cooled. Add more oil if needed until it reaches the “full cold” line shown on the expansion reservoir. 

You may need to repeat the steps to purge the air. Once your drive tires move at normal speed and the noise level seems right you can stop.

Steps to Change Hydraulic Oil on Exmark Lazer Z E-Series, S-Series- & X-Series  

Step 1: Park Exmark on Flat Surface 

Park your Exmark zero turn on a flat surface. You may want to place cardboard on the ground to keep spilled oil from penetrating the ground surface before parking your lawn mower on top of it. 

Remove the key and engage the parking brake. Wait for all moving parts to stop before working on your Exmark. Note the engine and transmission can be hot. Take caution when working around them.

Step 2: Raise Rear of Mower 

Use Jacks or another comparable item to raise the rear of the lawn mower high enough to get the rear wheels off the ground.  

Step 3: Remove Pump Drive Belt 

Step 4: Clean around the filters 

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

Step 5: Remove Filters & Drain 

Place an oil pan under one of the hydraulic filters. Unscrew the filter using a socket and let the oil drain. Repeat with the other hydraulic filter.

Remove the oil pan, and place the used oil back in the containers. Mark the containers to indicate the oil is old and plan on dropping it off at your nearest recycling center.

Step 6: Install New Filters 

Apply a thin layer of hydro oil on the rubber seal of the new filters. Install the filters by turning clockwise and torque to 14 ft-lb.  

Step 7: Fill with Exmark Hydro Oil 

Slide your seat all the way forward and take a rag and clean around the hydraulic caps located on the left and right-hand sides of the mower behind the seat. Remove the caps and fill them with Exmark Premium Hydraulic Oil until it reads full on the dipstick. Replace the hydraulic oil caps. 

Step 8: Re-install the pump drive belt 

Step 9: 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. Start your mower and increase the throttle to full throttle. Release the parking brake. 

Move the speed levers all the way forward for one minute. Turn off your Exmark, let the hydros cool, and check the oil level.

How Do You Release Hydraulic Drive System on an Exmark?   

Your Exmark stopped running and you’re stuck in the middle of your yard. Your zero turn is not moving even when you push it. 

In order to push your Exmark, you must release the hydraulic drive system. The procedure to do this is a little different with each model.  For more details, read (coming soon). 

Related Topics 

Winterize Your Exmark Lawn Mower 

When you get to the end of mowing season you may be tempted to just store your lawn mower in the back of your garage or storage unit and forget about it until next year. Read why you may not want to do this in “How to Winterize Your Exmark Lawn Mower”.