I've effected roadside repairs with Barr's Stop Leak on a couple of
occasions, once on a 70's Pontiac Ventura and another time on a Buick
Apollo. It definitely works, but it can only do so much. If it's a
minor leak past a gasket, it'll likely stop it up. It may come loose
later, but it'll work short term. If you're planning on keeping the
car, I would recommend getting it fixed properly. Stop leak stuff
seems like it's best for putting off the inevitable collapse of a car
on its way down. That Buick and Pontiac both lasted long enough to get
me to my destination, but they were pretty much doomed.

The PO of my Vanagon had apparently tried the stop-leak trick too, as
he was not mechanically inclined and had no money to have it fixed.
Possibly it helped, but it clogged the radiator too. Really what it
needed was new head gaskets. Instead, it still leaked like a sieve and
developed a cooling problem as well. Personally I think stop-leak is
an abomination that allows you to borrow a little time now, which
you'll end up paying back later it high interest rates. And newer
cars, it seems, are less tolerant of suck things than old detroit
rolling iron from the 70's and earlier. Unless you're looking to stop
the leak just long enough to sell the car, I'd recommend against it.

> Question. Are these coolant stop-leak compounds really effective? And
> what would be the prospects for stopping this leak with such a compound.
> 
> I confess I have never used such before and I am leery of putting
> something in  the system that might possibly clog the radiator or
> something.
> 
> Anybody had hands on expereince with some of this stuff?? Reommendations???