Thermostat Temperature

[daedalusminos]

Well I'm enjoying being a new A8 owner, but unfortunately it looks as if the thermostat is playing up (temp gauge creeps up, but drops back with interior heating on full).

Reluctant to pay approx £35 from an Audi dealer, I decided to go the local motor factor route, but does anyone know the correct opening temperature? It would appear 80-88C are listed and even the local Audi dealer was unable to confirm the temperature.

Jonathan