I was checking the radiator fluid level yesterday and noticed it was down about a pint, low enough that the cooling fins for the transmission were visible. This seems to be an on going problem, I thought the aluminum radiator I put in a couple of years ago would cure it, but no. when car had stock 3 core radiator it would always be well below the filler neck too. Essentials: Stock 300 with ST transmission Timing is correct, and no spark knock. Using original fan shroud and stock thermo fan (which blows very hard) Have a 16# radiator cap (Stant) per the manual Runs cool most of the time, around town with ac on it can get excited and go over towards 200 Running anti freeze and a can of be cool stuff I see ads for coolant recover systems, but it never explains how the fluid gets sucked back into the radiator past the radiator cap. Most appear to be nothing but catch cans. Goal is to have a system like on my more modern cars that is sealed and lets the fluid level rise and fall as needed. Is this possible? Going to get a new radiator cap just in case the old one might be the culprit, but I highly doubt it. Tried to find somebody to check the existing cap but no one seems to have a tester Car does not leak any antifreeze anywhere and nothing in the oil like water. Oh, have 165 degree thermostat in. Thanks for any ideas.