I think the radiator gets too much cold air when driving. It may be a possibility to use some cardboard to cover the grill (is it called grill? it is here at least). Please mount it on the INSIDE for cosmetic reasons. The grill is very easy to take out. Open the bonnet. Two screws as I can remember (after someone actually backed into me) and lift out after pressing it gently towards the engine bay. There is also a ventilation grill in the bumper that may deliver cold air to the radiator that may be covered with cardboard.
Anyway, I don't think there is anything wrong with the thermostat. There is just very cooled down coolant that passes through the system. My opinion though...
Morten.
Abarth alloys. Inter Alloy lowering. Phoenix Gold & Kenwood audio. Abarth steering wheel. Insane Dalmatian door and seat refurnishing
Projects: K&N induction kit, racing seats, exhaust, window tinting.