Let me start by saying that, I would not normally try something like this with my truck. (I am very Anul, and I've taken excellent care of it) I've been having problems with my heater core, (smell, and windshield fogging) and I have been dreading the job ahead. Well do to lack of time, and crappy weather. I decided to try this product I found at the local parts store. I did research on it before buying, and the reason why went with it, is because it doesn't have any pellets or metal shavings or anything like that. My understanding of the way it works is, after you completely flush your radiator,(I used Prestone flush and about a quart of Vinager) you let your engine cool, and then add the product. When the engine heats up, it causes the first part of a chemical reaction, the second part happens when the product comes in contact with air. When it does, it chemically welds itself to the surface and hardens. Pretty cool! Not only did it fix the heater core, but it has also fixed my serging problem I was having on the freeway.(I don't know, I must have had a slight leak in my intake or something) Anyway, WOW! This stuff really works. And if it doesn't they'll give you your money back. No I don't own stock, but I kind of wish I did. You guys can check it out for yourself at gouniversalproducts.com Trust me, I would never use anything that would hurt my ride.