2006 Subaru Forester car runs hot

First be sure the radiator fan is turning on. If it's not, running the heater fan on a higher speed will act like a small radiator and bring engine temperature down.

Next, have your mechanic perform a chemical test at the radiator to check for a leaking cylinder head gasket. That involves drawing air from the radiator through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow. Those gases can pool under the thermostat and prevent it from opening. Thermostats have to be hit with hot liquid to open. Hot air won't do it.