Packard Forum Index » Post-War (1946-54)

I've been using Permatex anti-seize for years on most of my threaded connections, both automotive and non-automotive without a problem. They specifically recommend it for spark plug threads; that's printed right on the jar. I recall reading or hearing somewhere that anti-seize won't affect torque settings either. I put it on the 359's spark plugs when I replaced them in 2006. It was still visible on the other plugs I pulled. I don't know why it seemed to fail with that insert or what caused the insert to split open in the second thread groove; neither the plug nor the insert was cross-threaded.

GM specifically advises against using anti-seize because the plugs run deeper into the head before achieving torque. After long usage the carbon build up on the exposed threads will lock and tear the threads out of the cylinder head upon removal.

So I would use anti-seize only when specified by the manufacturer.

Most of the Packard 12s with aluminum heads have been converted to larger plugs that won't break off in the head.