I'll jump in on this one with an experience. I had an 85 toyota p/u with the famous 22R engine and it blew a head gasket leak on the outer perimeter of the head. It was shooting a stream of water out as wide as your little finger. I had a friend who worked in a diesel shop I called. He came out , put in a jar of Bars Leak, filled it up with water and left the radiator cap loose. We started it up and within a couple of minutes the leak was completely stoped. Actually, it was less than that. I watched the stream just shrink and stop. I drove it to a shop and had it fixed. He said they used bars leak in all there over the road trucks and always had good service from it. I agree that I would not use it unless I had to, however it does a good job at emergency repairs but I would not depend on it for the long haul.
BTW, has anyone ever heard of using ?oatmeal I believe? or something like that in a radiator leak. I had a good friend who once did a cracked block with "sodium ?" and drove it 2 more years. It was a little ford pinto.
