Hydraulic fluid for old mower

[rjgogo]

I have an old Simplicity 4211 that I use to pull a cart and for close in mowing that I can't reach with my larger tractor. My guess is the fluid has not been changed in at least 15 years. It was a hand me down and runs great after a little tuning of the engine. I went to the simplicity site and could not find the manual that specifies what type of fluid to run. Any one here have a recomendation as to what to use to change the fluid?

Or since it has been so long could I be doing more harm then good at this point?

 

[Soundguy]

My bet is that any ATF ( F or dex/merc ) or UTF fluid will work fine for this type of app.

Soundguy

 

[DieselPower]

I would agree with Soundguy. You wouldn't go wrong with a UTF fluid.

 

[rjgogo]

Thanks for the responses, I emailed simplicity and they told me to leave it be as it is as long as I am not having any issues. I found that odd but then again I don't. The old fluid could be holding everything together. Thanks again for the input.