# Question on changing hydraulic fluid on a ZTR mower.



## jpollman (Jan 14, 2001)

Last spring we bought a Gravely ZT 52HD and it is a SWEET machine. I changed the engine oil on schedule during the season late last summer. But during the end of the season doing fall cleanup, the timer tells me that it's time to change the hydraulic fluid. I called the place we bought the machine and was told it would cost about $200! I called another Gravely dealer who's a little closer to us and he said that it would be $80 plus parts and that the filters are $30 each (needs two of them) plus the fluid. I found places online that I can get the filters for between $12-$15 each and the fluid is just 20W-50 motor oil with an API SL rating and I can buy that at O'Reilly for $4/qt. and it only needs about 4 qts.

I've read the procedure for changing it in the owners manual and it doesn't look too bad. The only thing I'm concerned about is purging the system after it's changed. I know a couple of you here have similar machines. Have you ever changed the hydraulic fluid? If so, how bad of a job was it overall? 

It will be time to start cutting before you know it and I want the machine ready to go when it is.

Any input is appreciated. Thanks!

John


----------



## mj6131 (Aug 30, 2009)

I don't think you want 20-50 motor oil for your hydraulics. While I have no experience with this brand, my experience with other hydro-drive mowers is that you want a hydraulic fluid that is labeled as "transdraulic" or at least mentions transmissions.


----------



## jpollman (Jan 14, 2001)

I went to the gravely site and downloaded the owners and parts manual. The instructions in the owners manual state that it used 20W50 motor oil with an API SL rating. 

At first it looked like it was going to be a real pain to do. But the other day I crawled under there and found that the access to both filters and plugs is pretty easy. I ordered a couple filters this morning. When they come in and the weather warms up, I'll get it changed. If I do use the 20W50 and something goes wrong, I'll fight it out with Gravely because that's what their instructions say to use. 

I don't think the purging will be all that tough either. It'll probably take me an hour and a half or so, but it's only going to cost about $50 tops. That's much better than the $200 that one dealer quoted me!


----------



## smith34 (Feb 2, 2009)

That type of 20w50 is normal for many lawn mowers hydrostat systems, even though it's a motor oil. I just did mine in a couple hyrogear units, same deal.


----------



## ESOX (Nov 20, 2000)

Run a quality synthetic, your clutch packs will thank you by living a lot longer.


----------



## walleye621 (Dec 30, 2010)

I have a toro Z and the dealer said just change the filter and watch getting air into the system. Refilled with Mobil 1 50wt i think. Napa should have a filter that is the same.

How many hours do you have?? For most residential use requirements i would think once every three years or 100 hours. Are you running in extremely dirty conditions?


----------



## jpollman (Jan 14, 2001)

walleye621 said:


> I have a toro Z and the dealer said just change the filter and watch getting air into the system. Refilled with Mobil 1 50wt i think. Napa should have a filter that is the same.
> 
> How many hours do you have?? For most residential use requirements i would think once every three years or 100 hours. Are you running in extremely dirty conditions?


No but I'm going by the maintenance timer on the machine. I've got 
a little over 80 hours on it. We bought the machine last April and it cost $5100.00 so I'm going to stay on top of maintenance by their schedule. It calls for first change after 75 hours, and then I think every 400 after that.


----------

