Going to keep this simple.
Your bleeder bolt's crush washer needs to be changed after every time you loosen the bolt. The bolt is an m6, however I can not find the copper crush washer anywhere. Coolant might not visibly leak from that spot if your torqued it down hard enough, but air WILL get in, causing bubbles in the coolant, and prevents coolant from being refilled into the radiator from the overflow tank. Fix is simple. AFter much searching, I couldnt find an m6 copper crush washer anywhere except in a honda fuel filter box.
#14 Galvanized Bonded Sealing Washer | Fastenal
These are availible at homedepot in the specialty bolt drawers. $.65 for a pack of 4.
Bring an m6 bolt, and get the ones (forgot which size) that fit very tightly around the bolt. I slapped these mofo's on and there was no leak, and coolant was always at a stable level.
These work great