[Chief of the 60's]

Washer bottles have been used as overflow bottles for decades. They sorta work but do not have good enough flow. I have a small black plastic one, like in the photo, that kind of hides next to my radiator. However, you can "catch" all you want but you will still be adding fluid if you do not run a closed system. To run a closed system you will need a closed system radiator cap.