Grandson is doing a full service on his 'new' WD Leroi tractor, I told him to use Universal Tractor Fluid (UTF) in the transmission and differential, also the hydraulic pump.

Grandson actually RTM (Read The Manual, now there's a concept!)   Seems the Operating Instructions manual we have (actually for the WD45) states to "Use SAE80EP all year."

Google tells him to use 75W-140, now he wants to drain the fresh UTF

Did I give him bad advice?

P.S. I tried searching this forum but the search engine stinks, it says I'm not authorized to do such heinous acts

Take my working CA for example: I bought it with gear oil in the trans (bad for the hydraulic pump since they share oil on a CA, unlike the WD... I'm sure you know this, but for anyone else's benefit if they are new to these tractors). It wasn't leaking but just a teeny tiny amount out of the PTO shaft seal. In this case, since a CA absolutely should not be using gear oil in the trans/hyd compartment, I replaced it with trans/hyd fluid because that is a better fluid for the application than the SAE 20W that was originally called for, and what needed to happen for my CA. No argument since the CA shouldn't have gear oil. I replaced the PTO shaft seal. Flushed everything out and put fresh trans/hyd fluid in it.

Now the tractor leaks from basically everywhere but the PTO seal, ha... Both axle shaft seals and the input shaft seal. Both lift cylinder seals. The gear oil wasn't leaking out of any of these previously.

I know many folks on here have had good luck with a trans/hyd fluid in place of gear oil. I think a lot of tractors don't really get worked and you're not going to know if the bearings in a trans with gear oil makes it to 10K hours but the trans with trans/hyd only survives 2K. But, honestly, it probably does not matter for a tractor that goes to a couple of shows a year and putts around the yard. Even then I wouldn't want to deal with the leaks unless I had replaced all of the seals recently!

I like your grandson. Manuals and reading are good things.

I'd run the UHF.  Dad has it in both of his.  No leaks, shifts smoother, and doesn't creep with the hand clutch.

AaronSEIA

The reason I use it is that I can stock one fluid, instead of several different ones that were originally recommended. (821 wasn't around until long after a lot of these tractors were discontinued.) I have it in my WD's, WD45's and CA's and every tractor I own. When I buy a tractor, everything gets changed to 821.

As I said, Doc recommends it. That's good enough for me!

Indeed!

Grandson is 15 years old, all of his life he has heard me rant about folks who won't buy a manual for vehicles, etc. Now I give him advice based on what I have read on this forum, which contradicts what he actually read in the manual! 

I do agree with DrAllis that lubricants have improved dramatically, and I am comfortable with using UTF in this application, which is unlikely to ever see thousands of hours of heavy usage, but I wouldn't place any large bets on that either, knowing my Grandson He just finished up a month of haying for a neighbor and was putting in 12-14 hour days.