I never had much faith in the 'Stop-Leak" products until two years ago when my old Pontiac developed a severe leak in the power steering rack. Fluid had to be added to the reservoir every day (the leak was that bad). I tried a product called "NO LEAK Power Steering Sealer for Amber Leaks", made by Gold Eagle, and purchased at K-Mart for $5.99. The leak completely stopped and has not returned in two years.
I think their web site is: www.goldeagle.com/leakstoppers