I just need to clarify that you understand the purpose of the radiator bottle. First, it always has coolant in it. If the level drops below cold, and you filled it to the cold level when it was cold, then you should worry. If the level stays the same all the time, don't worry about the overflow. Next, if the guage says it's running hot, you need to verify it with something like an infrared temp gun. Do that, then let us know the results.