Zoltan,
I'd recommend against using any of these as they reactivate old leaks, in my
experience. Prestone or the others work, but as they clean they also remove
whatever gunk is clogging your pinhole leaks. True, you could argue that you
shouldn't have these leaks to begin with, but many of us do, and do you
really want to tear down your engine to fix them once you've cleaned out
your cooling system? This is one of the few products I've had consistently
bad results with. I'm also not certain there are any great benefits to
rinsing with anything stronger than just water. My two forints.

Geza