can barrs stop leak be added to the radiator overflow tank?

Only if it is part of the system,a header tank(more than one pipes connected),e.g fords,vauxhalls etc,if it is just a reserve tank (connected by just one pipe to top of radiator,)but personally i dont recommend stop leak additives,as they can affect other parts like thermostats,its best if you can get the source fixed.

marcus the mechanic
January 2008