No I don’t agree. Kubota RECOMMENDS it but they don’t REQUIRE it . They recommend because it meets their spec and they do their R&D with their recommended oil. Why would they waste the time to do testing with the many oils out there?That pretty-well clarifies that either Super OR regular UDT must be used. ... Don’t you agree?
I do agree there is risk of warranty work being denied. This is just my experience in auto world, if it got as far a court due to this, Kubota would have to prove without a doubt that an oil they don’t recommend caused said damage. Do they have the money and resources to do so, yes. Is it worth it? Does it cost more then the warranty repair cost? (that I don’t know) Is it worth a relationship with the customer? These aren’t questions for you or me to answer though.
The customer is free to dump whatever fluid they want in their own tractor. They have to decide if the “savings” is worth it. Maybe they have problems, maybe they don’t
And I again, I know where my risk/reward value is, and I use SUDT 2