AFAIK calls for the red VW coolant (G12?) and not just a
could be coolant level low.
IIRC If you system originally had the red coolant in it and you add any other type of coolant, you might want to flush the coolant system before any chemical reactions occur within the cooling system turning it into sludge. BTW Did you use Dex-Cool or what?
I have seen radiator caps that could not hold the pressure anymore and it allows the coolant to escape. Did you see any residue of a leak anywhere? Esp. check any plastic coolant pipes on the cylinder head over the transmission. Does the temperature rise very close to the "hot" zone?
later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris