2019 3500 - Coolant Levels

[scubar]

Just now noticed my 2019 3500 Cummins expansion tank is at the low level (35K miles) and owners manual says to use OAT coolant meeting MS90032 spec.
Another source says to use coolant meeting MS-12106 spec. Any suggestions on where I would check to see if they are equivalent? Also noticed that the
expansion tank cap would not come off after several turns. I know this sounds stupid but Is it normal to have to force it off?

Found that the difference between MS-90032 and MS-12106 is that the 12106 is newer and has an additive that makes it taste bitter so that it's safer when used around pets. Still would appreciate any input about the difficult to remove expansion tank cap.