No, the cylinder head bolts and the head around the bolts won't be anywhere near 399F. That sealer is GM-recommended (but with a GM part number on a custom-labeled tube).
The actual exhaust ports may get really hot, but not the area where the bolts are. And certainly not the block, which is where the sealer on the bolts is screwed into.
The actual exhaust ports may get really hot, but not the area where the bolts are. And certainly not the block, which is where the sealer on the bolts is screwed into.
