Castrol is pretty adamant about not mixing coolant. I thought it was just commercialism, but speaking to customer services, apparently there could be significant issues with mixing different brands - things like complete separation or the stuff going glutenous and coating and blocking stuff to mention a few!
This is Castrol's specification for the Puma, but the website covers all vehicles from '92 onwards and the note 922 looks onerous enough!
Castrol Trade Australia - NetLube
Can't say I've seen it happen or experienced it, but I'm not going to take a chance:eek:

