Manage to get to the bottom of this? My v7 Sti got a little warm on Friday while I was going away for the weekend. Was while I was going up a hill slowly behind a truck, defi water temp gauge went up to 100 degrees. Factory cluster water temp gauge didn't move from halfway. Radiator is a redline Ali one just over a year old and had cambelt water pump and thermostat done at winger few thousand km ago. It put a little bit of water in the reservior and was still fill in the filler tank. Going to get a new factory sti radiator cap and see if that will help.
What is the normal operating temperature?