Looks like I had green coolant in there but my local auto store only had:
Prestone® MAX European Vehicles (Blue) Antifreeze + Coolant
Am I screwed? Should I drain it ASAP?
Edit: the large tank was basically empty so I doubt any mixed yet but there was still some in the smaller tank
I don’t know what your X3 calls for, but you could just drain it and flush with distilled water before putting the correct stuff in it.