Case Hytran oil should be around $60-70 for 5 gal.
I bought a 1370 Case a couple of years ago and replaced the oil with what I thought was a premium oil.
I’m currently rebuilding the entire rear end because the oil I used eat every paper fiber disc in the tractor.
The old 830CK tractors are less forgiving because they DO NOT have internal brakes and differential clutch plates like my 1370 but they still can benefit from HYTRAN.
Hytran absorbs moisture, does not contain zinc which causes corrosion thus protecting your hydraulic valve spools, rear end bearing etc…
Personally I would suggest you call a couple of Case IH dealers and see what kind of price you can get on Hytran.
If you still want to go another route then buy an oil rated for your application and don’t mix.
Labor and parts cost a lot of money these days and its worth protecting them from undue wear and corrosion
Just my opinion, I hope this helps