Thermagasket?

Anyone ever try rxauto.com's thermagasket? If so, got any advice, warnings, testimonials?

Thanks

I dunno, it's an additive that enters the coolant stream and seems to be similar to Bar's Stop-Leak. While it may be fine for small leaks, I personally doubt it will do the job for a cracked head or really bad head gasket.

I would hesitate to drop $100 on it, without first checking the ride with a trusted mechanic.