Don't know anything about Kubota coolant requirements but I switched over to ELC coolants on all the vehicles I service. My favourite is Detroit Diesel PowerCool Plus which I believe is the same as Peak Final Charge.
2006 GMC Sierra 4.3l, NV3500,G80 , Formula Shell Synthetic 5W30,Dexcool.
1987 BMW R80 - sold
2015 Honda CBR300R
Staying out of the right lane a lot.