i asked the parts store counter man about blue devil a while back and he said it really works, and works so well, it was off the market for a few years because it was taking money away from repair shops. the only drawback is that you must follow the directions to a tee and you must open up the system after youve added it and let it dry completely for around 2 days it think it is. its not cheap at $60.00 a bottle but thats alot cheaper than a gasket job these days.