Using oil or transmission fluid in hydrostatic transmission.

[Bill Sherman 11]

I have a 1979 C-161 automatic that still has 10w30 oil in it.  What are the pros and cons of converting it to transmission fluid?  My school of thought is if it's been working fine with oil in it then why change it?  Also, it was designed to run on 10w30 so would converting it cause problems?  I just wanted to hear what people who know more about Wheel Horses have to say about the subject.  Any input is greatly appreciated.

[squonk 41,287]

Leave it at 10/30. If you want to change it use Mobil 1

[wallfish 17,075]

If it ain't broke, don't fix it

[rjg854 11,451]

I hear that if you have oil in your transmission, it should remain oil. Doing otherwise would cause problems, the 2 don't mix well. 

[oldlineman 1,482]

[Cvans 1,009]

South Carolina doesn't get that cold so why would you want to change. I run ATF in some off my GT's (not Wheel Horse) but it gets well below zero here. 

21 hours ago, wallfish said:

If it ain't broke, don't fix it

[WHX?? 49,100]

Another vote for 10/30 here as pretty sure that what the book says. Make sure the cooling fins are clean & fan is on it.

[Bill Sherman 11]

It’s not that I want to change it.  I had just heard some people have done it and I was curious as to why and if it was better than using oil.  

[953 nut 55,699]

23 hours ago, Bill Sherman said:

it was designed to run on 10w30

It was designed to operate properly with 10 W 30 and has done so for four decades;   Don't Mess With Success!

[WHX?? 49,100]

Can't explain why some guys would want to switch. but some hydros, namely Sunstrands did specify to use ATF.  It would only be more beneficial if the OEM called out for it or a service bulletin was issued to switch it.  

[cleat 6,296]

My Ford LGT165 used ATF and it also had an Eaton 1100 hydro.

 

It moaned and groaned a lot where all of my Wheel Horses are virtually silent.

 

Other than the possible slight delay with the lift, I think the 10W30 is the way to go.

 

[Bill Sherman 11]

I’m just going to put Moble 1 synthetic 10w30 oil in it when I change it.