Ok.. I ahve had seveal lunch meetings with a Chevron engineer over the last year or so... Chevron makes the oils for Kubota. The oils for Kubota are actually formulated, tested, and engineered in Chevron labs in Japan..
I asked him the other day about the Kubota UDT and SUDT, he enthusiastically stated that it was absolutely the best oil you could buy for your tractor..
I asked why the cost was that of a synthetic, he stated that it was the additive package.. there was no hesitation in his comments.. it convinced me that I am not interested in putting anything else in my Bota... We spent alot of time discussing the differences between CI and CJ rated oils as well..
Ashland (Valvoline) makes the UDT, SUDT, SUDT2 and all their engine oils for Kubota. Says so right on the MSDS's. Puzzling why a Chevron engineer would think his company makes it
Kubota Safety - Material Data Sheets