figure if dads unit is bad I can swap in this unit. Or put it on eBay.

20W50 synthetic is a good choice for the hydro side. Whatever you find closest to the 90 weight gear oil for the differential is fine. Last I saw the bellows kit had gone up in $ quite a bit, but it has been a couple of years.

Bellows cover has note that removing voids warranty. Pulling trans was pretty easy. Not a yearly job though. Maybe every 5 yrs? Pops unit has snowblower, no mowing deck. Did find 2 identical riders for sale. 1 had no motor or deck. 2nd had both both but bad hydro. $40 for each. Or offer on parts. Found a newer model too but it had spicer trans. Different lever positions. Seller said hydro works fine. He bought it for motor.

Thank goodness it's close to 20 years out of warranty!

Put unit #2 in. Moves fine now. Unit 1 fluid looked about the same. Might fiddle around with it when I have time.