Auto trans hydro fluid

notjustair · Apr 2, 2016

I'm still pondering the same hydro but thought I would bump it up to ask another question.

The hydro units use a common overflow tank and take type F auto trans fluid. If I'm right that's 10 wt oil. The suggestion was made by several to run thicker oil in it. Is that going to cause a high pressure situation and make the shaft seals implode? I'm also wondering if it will foam in that environment. Would I be better off running a 20-50 synthetic oil in it?

504 · Apr 2, 2016

Type F is not as slick as other ATF fluids. The hot rod tip back in the day was drain the GM fluid out and add type F(harder shifts less slippage)I would not add synesthetic, IMO.

Bob · Apr 2, 2016

I would not be afraid to try the 20-50 synthetic.

Dunno if it will enough "thicker" to make things better, but it ain't gonna hurt anything to try.

Brendon-KS · Apr 3, 2016

Hydrostatic systems aren't as picky about what kind of oil they use as what some folks would think. As an example, Danfoss approves a wide range of oils for use in their pumps and motors including various grades of engine and hydraulic oils, ATF, universal tractor fluid, and various bio oils. The important thing is that the viscosity stays in the correct range over the entire operating temperature range. If you don't operate your machine in extremely cold conditions a more viscous oil should not be a problem. You might put a gauge on your case drain line - if the pressure stays below 50 or 60 psi during cold starts and gets down to no more than 20 psi or so when warmed up your shaft seal will be fine.

MarkB_MI · Apr 3, 2016

What do you have to lose? You're already looking at replacing or rebuilding it anyway, right?

Recommended oil for Hydro-Gear transaxles is 20W-50, so it's not like you're going too far out on a limb.

Determined · Apr 3, 2016

(quoted from post at 22:51:26 04/02/16) I'm still pondering the same hydro but thought I would bump it up to ask another question.

The hydro units use a common overflow tank and take type F auto trans fluid. If I'm right that's 10 wt oil. The suggestion was made by several to run thicker oil in it. Is that going to cause a high pressure situation and make the shaft seals implode? I'm also wondering if it will foam in that environment. Would I be better off running a 20-50 synthetic oil in it?

Don't know if it will work on your application.
I have had several Case 442 and 444 garden tractors, with hydraulic fluid in them they will start off moving ok but as soon as the fluid starts to warm up they feel like they are slipping and can barely move.
Drain system and refill with 15/40 and it feels like a brand new machine.
Bought one over 20 years ago that could not even drive onto a trailer, only thing I did to it was change oil to 15/40 and to this day with loaded tires and chains on the rear it still has enough grunt to tow trucks into the shop.

Auto trans hydro fluid

notjustair

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504

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Bob

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Brendon-KS

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MarkB_MI

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Determined

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