I've spoken with a representative of Kubota at their main U.S. number and he confirmed that Kubota UDT2 oil is made for Kubota by Valvoline. Where do you, however, buy that product?
News to me; and I work closely with Kubota. It may be MADE by Valvoline, but that doesn't mean that the valvoline that you buy at TSC or wherever else is the same stuff.
I have a M9540HDC in the shop right now. The owner complains that when the tractor is cold, it will not move. Put it in either forward or reverse, let the clutch out, and the tractor sits still for about 5 minutes. Then it grabs and starts working 'normally'; and grabs pretty harshly. I have verified this and it does exactly what he says. So I am looking into it. WIX hydraulic filters. WIX engine oil filter. Wix fuel filter. Tells me that it's probably got some universal tractor fluid in it. I loosened one of the wix hydraulic filters, and the stuff came out like honey. It was about 65 degrees F oil temp at the time; so it should have flowed just fine. Called customer and asked him what oil is in it. Yep. TSC oil that says "compatible with Kubota UDT". Gave him estimate to drain and refill (about $375) with super UDT; with no guarantee that the shuttle clutch will work after the fluid change. The other option, split tractor and inspect the shuttle clutch. $1500 minimum, give or take, + any repair parts, sealants, etc. He says try the SUDT2. Drained the oil, which by the way took about 3 hours because the stuff would NOT drain very fast. Replaced filters and then refilled with SUDT2. Fired it up, lifted the shop door and drove right on out with zero problem, works normally. I'll try it again in the morning after it's sat all night but I don't foresee any issues.
About 3 years ago I had a guy ask me about UDT and why it's so expensive. Because it's good stuff, and that is no lie. He didn't believe me and went out & bought some stuff from Oreilly's, changed his fluid and filters and went on about his business. L3010HST. Last year he calls me and asks why his hydraulic system is kind of weak and why his HST oil is leaking from the bellhousing. I have seen the bellhousing leak before, and did not have a cut-and-dried solution, so I called an engineer I know that works in Georgia (for a tractor manufacturer). He asked what kind of oil-and went on to say that the oil quality depending on what is in it, can cause the little rubber lined collars to slip down the propeller shaft, causing oil to leak into the bellhousing. I advised the owner what I was told. I'm not an engineer...so I can't say for certain that's what did it. He agrees to let us repair it at $2000 (including new clutch) and we refilled it with SUDT2. Guy calls the day after he gets home and wanted to know how we made the transmission work so much better, he says there's no more waiting for it to build pressure, no noise, the loader works 10x better, 3 point works immediately after starting the engine. All I did was put a clutch in and replace the propeller shaft, and refilled the trans with SUDT2.
All of the BX's I've worked around, they can get a little noisy, but owners tell me that SUDT2 quiets the noise considerably; and the tractor works smoother.
Need more examples? I've got a few decades under my belt working with these things and I can give you a bunch of examples. Heck we used to fill the J.D. 4000 series E-HST transmissions with SUDT as JD was having some problems with low-vis Hy-Gard there for a while. Amazing how much quieter they ran with SUDT2 in them.
I have a T1560, bought it with transmission problem. Pulled trans, replaced broken shaft, refilled with SUDT2. Works a LOT smoother, and quieter, and actually has more pulling power. With the recommended 20w50 (from hydrogear's recommendation), it's really noisy and real sluggish when cold. Both of those "normal" characteristics are now solved with SUDT2.
Massey Ferguson 1145 tractor (mine). Drained fluid, replaced filters, and refilled with SUDT2. Shifts better, PTO clutch works a lot smoother, etc...way better than permatran III that came out.