Here's the magic formula...
(PER PADDLE)-- 1 bottle of Liquid Alumaseal Radiator Stop Leak (or Bar's Leak), mixed with 15 ounces of regular Anti-Freeze (non- Dex),.. I use Peak brand.
You have to stir the Alumaseal with a screwdriver to get the stuff in the bottom of the bottle blended with the liquid. Then pour it into an old gear oil bottle along with the Anti-freeze, and use the gear oil spout tip with 6" of vinyl tubing to connect to your valve stem (core removed), then squeeze the bottle 'till empty. You HAVE to shake the bottle alot to keep the stop leak in suspension. Drive the car a mile or so and you're done.