Got a 2008 yesterday. 170k. Almost new tires. Probably head gaskets. Battery was 4volts. Got it started. Runs fine. Yes coolant fluctuates from 200-220f. Surge tank did rise when hot. Fans are running. Hoses are hot.
Looking for info is all. That you did 6 now I am asking why. If overheating and you found head gasket replacement is the answer, great. But did I miss the temp after the head gasket job done to show you fixed a problem that came from the factory as I do not hear of head gasket jobs being done this early in the milage. Did you also change the thermostat?