Hydro-Gear oil..which to use? - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information
Thread Tools Display Modes
post #1 of 6 Old 05-03-2010, 11:30 PM Thread Starter
MTF Junior Poster
Join Date: Apr 2010
Location: IN
Posts: 7
Hydro-Gear oil..which to use?

Ok, so I've read all the threads that say anything about hydrostatic transmissions. I've got a 2003 GT 5000 with the 331-3000 hydro-gear transmission. My question is, If the transmission comes with 20w-50, do we HAVE to put that back in it? Is the hydra-static fluid we see at tractor supply stores sufficient?

Can we use AMSOIL (Synthetic Tractor Hydraulic/Transmission Oil
SAE 5W-30 (ATH)) :

or perhaps Mobil 1 15w-50 dino?

or Shell Rotella-T 15w40 dino?

or just plain Valvoline 20w-50 dino?

you get the drift...

I just dont understand the integral mechanics of our transmissions so, I want to be sure to put the best thing in it. Thanks a lot guys

Last edited by wj52083; 05-03-2010 at 11:36 PM.
wj52083 is offline  
Sponsored Links
post #2 of 6 Old 05-04-2010, 01:03 PM
15,000 +posts!
Tractor-Holic's Avatar
Join Date: Jan 2008
Location: MA
Posts: 16,383
Re: Hydro-Gear oil..which to use?

I'd stick with what is reccomended..20W-50 is thick,and anything with less viscosity might bring on trouble with an older tranny,that probably has some wear in places that are critical like the pump,and any loss of pressure will affect its ability to climb hills or pull weight,etc..the pumps on hydrostatic garden tractors aren't rebuildable for the most part,and once the housing gets worn,its disposeable..thicker oil might give new life to one thats worn some,thinner oil will make it worse instead of better..Synthetic oils might resist viscosity breakdown better,but you might have "fun" finding any 20W-50,most are much thinner and cover wider ranges of viscosity,I think "regular" oil is what I'd use in 20W-50 grade..
Tractor-Holic is offline  
post #3 of 6 Old 05-05-2010, 02:43 PM
Senior MTF Member
pylek's Avatar
Join Date: Jun 2008
Location: South Carolina
Posts: 604
Images: 26
Re: Hydro-Gear oil..which to use?

For what it is worth, the last two Hydrogears, and the next one, that I put together got filled with Valvoline synthetic 20W-50, ordered through my local NAPA.

Seth K. Pyle

Nothing is sailor-proof...

2002 Craftsman LTX1000 with 21.5hp Intek Twin
1994 Craftsman LT1000 with 15hp OHV single
1979 John Deere 317 C317H soon to have an M18
1986 Craftsman II GT18 917.255912
1987 Craftsman II GT18 917.255913
1988 Roper GTK181AR with a Kohler M18 Magnum
1993 Craftsman GT6000 with a Kohler M18 Magnum
2002 Craftsman DGT6000 with a blown Kohler 27hp Command Twin
2004 Craftsman DLT2000 with a Kohler 25hp Command Twin
1993 Hechinger (MTD) 16/42 with 16hp Vanguard Twin
pylek is offline  
Sponsored Links
post #4 of 6 Old 05-06-2010, 12:49 PM Thread Starter
MTF Junior Poster
Join Date: Apr 2010
Location: IN
Posts: 7
Re: Hydro-Gear oil..which to use?

cool, thanks guys, I found some Lucas 20w-50 synthetic ($6.99/qt) at O'Reilly Auto Parts. should do the trick.
wj52083 is offline  
post #5 of 6 Old 05-06-2010, 08:49 PM
TECH Exchange Contributor!

Alan Lloys's Avatar
Join Date: Sep 2009
Location: Wisconsin
Posts: 582
Re: Hydro-Gear oil..which to use?

Stick with the recommended weight oil (or close to at least).
I filled two GT5000 transmissions with Mobil 1 15W-50 oil.
I decided that the minor difference between 15W and 20W was not a concern.

The tractors ran great after that and from what I know are still running strong after I sold them.

There is a trick to replacing the oil in these. If you run it for a while to get the oil warmed up you will save a bunch of time. Then park the tractor over a catch pan and drain it by loosening the two allen head screws that holds the gerotor cover on. It is the little black lump at the bottom of the transmission. Just loosen them a little, you don't want to take it off completely.

After it is empty you can close it up again and refill through the breather tube connection on the top. Fill until oil comes out of the oil level hole (brass colored plug).

Hope this helps.
Alan Lloys is offline  
post #6 of 6 Old 05-06-2010, 11:17 PM
Senior MTF Member
Join Date: Feb 2009
Location: Ohio
Posts: 129
Re: Hydro-Gear oil..which to use?

I have a DGT6000 with hydrostatic which I use for mowing and bulldozing in the summer and snow blowing in the winter. It worked great in the summer, but by the third winter the temperature went down into the teens and the tractor would move slowly going forward and just creep in reverse, both bad for snow blowing. It would get stuck on a wheel track in reverse and barely push into the snow going forward.

After much research, I went with Castrol Syntec 5W-50. It is the oil I already use in the engine and it works great in the transaxle, summer and winter. The transaxle had the same pep forward and reverse in the winter that it has in the summer and it runs cooler in the summer.

As far as the oil weights go, the second number in this application is the important one. It needs to be high, at least 40 but preferably 50. This is the viscosity of the oil when it's hot. The first number, the one followed by the W, is weight equivalent when the oil is cold. If you run it during the summer only, a 20W or 30W is fine. If you're looking to run it in the winter, too, you need to consider a 0W, 5W or 10W. Whatever you use, synthetic is better for the transaxle, and engine, than conventional oils.

As Alan Lloys said, the easiest/best way to drain the oil is to loosen the allen head screws and let the gerotor cover drop down, but be very careful to NOT let the cover come off. The oil will be draining very slowly so let it go overnight. You will get between two and four quarts of oil, depending on the capacily and how much oil is left.

You never mentioned why you're changing the oil. Normally, the oil is supposed to last for the lifetime of the transaxle, but that is not true, and it must be topped off on occasionally.
Runningbare is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome