[rdorman]

I would agree with Scott that the OEM type set up is not the ultimate, but is works for most of us. If your system is exchanging fluid with the overflow, then you could have a couple of other issues. Leaking head gaskets, steam pockets, water pump cavitation come to mind. Head gaskets you know how to fix! Steam pockets are often fixed by running a lot of block pressure (restriction on the exit). Water pump cavitation usually is helped by a quality high performance pump and by slowing the pump. A swirl tank will help remove air from the system no matter where it is coming from (address the problem first). By the way, it can often take a dozen or more heat and cool cycles to eleminate all the air in a system.

The only time I remove the radiator cap is either to test it or to refill the system. I know the system level by the over flow tank.