Many folks will say that fast fix products aren't good but I've excellent results on diesels with the radiator fix that looks like ground aluminum in a film canister (Bars-Leak ?). I don't follow the directions but rather use just a little at a time till the leak stops. I have a JD tractor that had a branch go though it's $600 radiator, Bars-Leak fixed it right up. I thought it was going to be a temporary fix, that was 20 years ago, no leaks or cooling problems. Coolant has been changed and flushed many times with no leaks nor addition of any more stop leak. I've probably used the stuff on a total of ten rigs in my life with 100% excellent results.