There is a product advertised to seal crakced engine blocks, lifetime garantee, only $100. The 1998 Honda Accord LX in question is presenting with oil in the radiator (frothy, brown gook). The radiator was replaced 3 months ago when we bought the car from a dealer. I am told the problem may be the head gasket or it could be as bad as a cracked block. It will be $1200 to do the head gasket, but it may not solve the problem. Has any one ever tried this sealant product? The car is for my 17 year old son to take to college (125 mile trip one way) needs to be reliable. Please advise.