CJ-4 is was not recommended for the new Tier engines - due to the chance it would damage the anti-pollution equipment. Thus it was a huge CYA for Kubota.
Then it appears they changed their tune.
read this ...which is FROM Kubota....
https://www.kubotausa.com/service-support/maintenance-schedules/lubricant-maintenance-schedule
And for what it is worth.....I would NOT run a 10w30 oil in the climate you are working in
I would jump as fast as I could jump to a 5w-40 weight oil....which is very easy to obtain and your engine will be better lubricated....when your temps fall below zero - your engine will love you for it!
Personally I would get some Rotella T6 or better yet......Amsoil 5w-40,
dont let the price tag fool you - you can get it cheaper (then again the Canadian dollar might be much different)
https://www.amsoil.com/shop/by-prod...e-series-max-duty-synthetic-diesel-oil-5w-40/