Last time I checked with Kubota dealers SUDT was not even available in Ontario Canada. The Kubota dealer I buy my supplies from recomends CASE Hy-tran for my Kubota because it is superior to SUDT. That tells me that there are options but SUDT is not one of them up here. You'd think if cold weather required SUDT then we'd have the stuff.
SUDT is the only Kubota hydro-fluid sold in Canada. As was said, I think they call it premium. Its bottled by a different supplier than whats sold in the US.
oil does go direct now, that I know. We stock 55 gallon drums, you can always get them from a dealer in smaller lots. I've not heard anything about oil analysis, but I could count the number of warrenty transmission problems we have in a year on one hand.