My dealer doesn't even stock the SUDT only UDT. He says in our climate it isn't any better than the UDT. SUDT and SUDT2 are basically for really cold climates being multi-weight oils rather than single weight like UDT and most other universal hydraulic oils. I recently switched from UDT to Universal hydraulic fluid in my
B26 and I cant tell any difference in performance, whine, or anything else. Those of you who claim to have better performance, go for it if it makes you sleep better at night. I have another $35K tractor that uses universal hydraulic fluid also and no problems with it either. Unless the OEM calls for synthetic oil, there is no need to spend extra for it, IMO. My universal fluid meets the spec for UDT and many others at least according to the labelling and I have no reason to doubt it. After all, Kubota oil is not made by Kubota and likely is made by a company that bid the lowest price to meet the Kubota spec. I do know that they have switched manufacturers a time or two in the past likely just to save a few pennies in cost so the dealers could make a little more profit.
I am all for supporting my dealer but not enough to pay double or triple the cost for similar if not identical oils. I do buy my filters from them rather than go thru the hassle of finding an equivalent even though they are likely double in costs from a WIX or other after market.
By the way, the Kubota shop manager himself told me that using universal hydraulic oil will not harm my tractor in any way. He did say that to avoid any warranty hassles to stay with Kubota oil till warranty expires which has long passed for me.