Last time I had that issue was on a Mazda Pickup. It was a Blown head gasket and the coolant was going out the tail pipe. I didn't catch it until I smelled anti freeze in the exhaust.
If its a cracked head or a bad head gasket I don't think putting stop leak will do anything except gunk up the radiator IMO. Sorry...Tjthanks for all the help... is a stop leak product a good idea for stopping the bleeding until i get to the mechanic. i have read both good and bad things about them