I use RTV. If it's around high heat like exhaust, I use Red RTV.
I've been tellin these guys for years GM stopped using liquid teflon sealer in the early 90s because they were finding it drying out and leaking. I kept copies of the TSB for years, but I threw my book out a long time ago. They recommended cleaning off the offending sealer, replacing gaskets if necessary and using the GM silicone RTV.
