Thanks for all your videos, live answers, & questions answered. I asked about head gasket additive Blue Devil for preventative use, forgetting about your Steelseal recommendation. I called Steelseal's tech support about that and your answer but said not to use it until I start needing to replace about a cup of coolant in the radiator top quite regularly and that would be the best indicator of head gasket failure starting that Steelseal would fix. He would have liked to sell me their product, but he was very honest and helpful like you. Just thought I'd pass that along and I mentioned your Steelseal video Youtube recommendation, too.