My Kubota dealer in Arkansas doesnt even stock SUDT and says we dont need it for our climate, however several folks here on TBN claim it makes the HST transmissions quieter. Personally I can live with a little whine rather than pay the extra $$$ for SUDT. My dealer service manager even said that if the tractor is out of warranty, you could use a universal oil that meets the UDT specs and it will be just as good. KUBOTA would use that as an excuse to deny a warranty claim if they found a none Kubota oil should a problem occur. My tractor is out of warranty now so my next oil change will be with universal hydraulic oil meeting UDT specs.