I had a pinhole in my radiator and it's an older car so I didn't want to spend a lot of money on fixing it. I read some reviews and decided on this product based on reviews here and information and guidelines on Bar's website. I added the product to my radiator, and once it heated up, it started to leak, after about a minute, the leak stopped. I let it run for about 20 minutes and no leaks!!! WHO-HOO!!