Hi got a new thermostat fitted to my a4 1.9 tdi the other day because temp gauge wast only sitting at 70,now it sits bang on 90 but after driving about 60 mile coolant warning came on so i stopped and it was low so topped it up and caried on by time i got home it had only went down a tiny bit,following day i did same journey and coolant went down in reservoir about half inch,now few days later its not going down atall,it whent back to garage this morning and he told me theres no leaks it must of been an air lock thats caused it to drop.
Does this sound possible as iam a bit nervous about letting girlfriend loose in car if its needing topped up,seems ok now