How to change hydraulic fluid in zero turn mower

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Most transmission problems in zero turn mowers are often caused by expired hydrostatic fluid.

You, therefore, need to swap out your tractor’s hydro fluid after running it for the number of hours recommended in your specific model’s owner’s manual.

Below we teach you how to change hydraulic fluid in zero turn mower after hitting the service hours mark indicated by the manufacturer of your z turn. 

How to change hydraulic fluid in zero turn mower

To reiterate, the best way to approach this chore is to follow the step-by-step instructions in your unit’s operator’s manual.

You should hence check the pages explaining how to go about changing the hydro fluid in the manual for detailed information before proceeding.

The good thing is that changing the hydro fluid in most zero turn mowers is pretty much like exchanging your car engine’s oil– It’s a pretty simple process involving just a few procedures and it needs few tools to complete.

With your owner’s manual guiding you, here is exactly how to change hydraulic fluid in zero turn mower:

Side Note: If you misplaced your manual but you can recall your zero turn model number (where applicable), search for a copy (using the model series/number) on the manufacturer’s website.

How to change hydraulic fluid in zero turn mower – step by step

Preliminary preparations

To begin your DIY hydraulic fluid change, warm up the engine for up to 5 minutes.

This gets the fluids circulating properly and it will help the fluid flow out of your engine easily.

Next, park the mower on level ground.

Now, shut off the mower’s engine.

It’s a good idea to wait for the engine to cool before touching it- You don’t want to burn yourself by attempting to work on the engine when it’s still so hot. 

Lastly, remove the key and proceed to engage parking brake to prevent the mower from rolling or shifting while you’re working.

Then, complete the steps below to change your tractor’s hydro fluid:

1: Locate the drain plug

The first step is finding the drain plug for your mower’s transmission system. Your manual should point you in the right direction here.

If you are unable to reach the drain plug readily- this is often the case in many zero turns- you’ll need to jack up the mower just high enough.

Keep in mind that you should not rely solely on mechanical/hydraulic jacks when raising your mower deck as they may not be strong enough to support the mower. 

They could also malfunction causing the mower to fall, which may cause injury.

The best solution is to use equivalent support or adequate jack stands.

Quick Tip: The drain plug is commonly located under the hydraulic oil reservoir in numerous zero turn mower models. 

2: Place a suitable container underneath

Next, place a bucket (or any other type of container that can function in a similar way) underneath the hydro oil drain plug.

The purpose of the container is, of course, to catch the fluid when it starts to come out. 

Quick Tip: You want a container that catches all the used fluid so ensure it’s big enough.

3: Unscrew the plug 

First, take off the hydraulic oil reservoir filler cap.

Then, protect your hand using a rag or even paper towels (and don’t forget to be alert as you’ll need to move the hand out of the fluid’s way when it starts to flow out).

Now unscrew the plug- you can use a wrench for this- to allow the transmission oil to start draining from the drive system into the oil-catch drain pan or collecting container.

Let all the hydro fluid run out.

After the fluid has fully drained, you’re required to carefully wipe the area around the filters in some models. It will help prevent dirt or other contaminants from entering the hydraulic system.

Depending on your specific make and model, you may also be required to remove and then clean the unit’s transmission sump screen (Some Cub Cadet zero turns need this extra procedure).

4: Remove the hydraulic oil filter

The next step in most models is to locate the main hydraulic oil filter and remove it. 

It’s usually similar to automotive spin-on type filters and is found just in front of your hydraulic reservoir. 

Find the filter and unscrew it – an oil filter wrench should suffice for the task.

5: Replace the main filter

Smear some little amount of fresh hydraulic oil in the area around the hydraulic oil filter’s gasket to lubricate it then refill the filter- only fill it with clean oil. 

Now hold the replacement filter in an upright position to avoid spillage then screw it onto the oil-filter adapter/filter housing. 

Here you should use your hand to spin it until the gasket (on the filter) makes contact. You then tighten it another ¾’s to one turn.

6: Replace the drain plug

Re-install the drain plug and refill hydraulic oil until it reaches the appropriate level – use the suggested hydrostatic transmission fluid for your specific zero-turn lawn mower only or its equivalent.

When done, replace the reservoir’s filler cap and tighten it appropriately.

7: Start the engine

Start up the lawn mower engine and allow it to idle for about 30 or so seconds to purge air.  

Some models need you to idle the engine for about 2 minutes so it is important to check what your manual says- the purge procedure varies significantly so we cannot emphasize enough the need to correctly follow the manufacturer’s instructions. 

Quick Tip: All purging should only be undertaken with the mower at idle speed. If not, damage may result.


You have successfully learned how to change hydraulic fluid in zero turn mower all by yourself! 

And oh, please observe each safety precaution featured in your owner’s manual.

As a final procedure, dispose of the used hydraulic fluid properly- take it to a nearby auto supply store or your most convenient oil-recycling center.

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