Had to take a trip yesterday of about 80 miles each way. Happily driving along at 70mph and all was good, got to the first town and decided to stop and grab a drink. Started to smell something weird and was horrified to see the temp needle at high. Parked up and let the car cool down, checked coolant level all was good. Carried on with our journey and as long as the car was moving it was okay but creeped high at lights. Got back home and changed the thermostat, drove around town and all good.

Had to do the same drive today, again all good on the motorway but in towns it overheated. Went to a mechanic out of town and he said it needed burping and all would be good, he burped it with no charge and we started to head home. Again motorway speeds it's perfect but overheating at stops.

Went straight to my own mechanic and he said considering I replaced the thermostat he believed it was the radiator. So I gave him the go ahead to replace it, he gave me a call a few hours later and said there was bad coolant flow and my radiator was all blocked up, no blockages elsewhere. So a new radiator was fitted cost was $390, no idea if that's cheap or expensive but relieved it's not the head gasket.