Nulon Radiator & Engine Block Stop Leak

This stuff may have changed my mind – Being a mechanic I never believed in a "mechanic in a bottle fix" we purchased a bobcat 3 years ago with a suspected blown head gasket. It would run fine but get hot and push water out all the time. Today I put a bottle of Nulon radiator and engine block stop leak in ran it for 15 mins, it went straight up to just under hot where it always runs. Turned it off. 1 hr later jumped in worked it for over 2 hrs and it never went over half on temp gauge and didn't push a drop of water out!! This stuff may have changed my mind....