I fill up the antifreeze in my car all the time. I probably fill it up every 500 miles or so. It has been doing this for over a year so I'm pretty sure it's not the head gasket. Plus I just replaced that a couple of years ago. There is never any antifreeze on the ground under the car either. Does anyone know what I have to replace so I don't keep spending so much money on antifreeze? Thanks!