I agree. Any decent gear oil would do. I'd probably use readily available 75w90 or 80w90.
Those are killer transaxles, I believe made by Peerless. I know the 1970 model year JD 110 my family had for many years was a 4spd. 1st gear was an extremely low creeper with 2, 3 and 4 being usable.
The variator gimmick was supposed to give you infinite 'ranges', but usually just screwed things up. You generally hoped no one yanked the variator lever back because like all variator systems on lawn/garden tractors, that center, moveable sheave would lock up on you, and you'd be left crawling along extremely slow.
Belts did last forever on these beasts.
Joel