My machinist recommended the use of Permatex "Indian Head" gasket shellac on my head bolts. On these forums, I've only heard people advocate using a liquid Teflon sealant, like Loctite PST or the Permatex equivalent. I don't think that Indian Head hardens. The bottle says "for use in threaded applications." Will the brown goo that is Indian Head work? In several posts, RB83L69 has spoke of using some brown stuff called Permatex 300 -- I wonder if they aren't one and the same? How much will the sealant throw off the torque specifications?

I've used a lot of different stuff to seal up head bolts, including that nasty brown goo. It never totally hardens and you will have no problems with it. Won't affect your head bolt torque spec.

Stuff also works wonders sealing up sensors that screw into coolant passages of all kinds, oil sensors, etc. It even works on areas that are immersed in fuel (fuel line fittings) which RTV isn't recommended for.

Indian Head gasket Shellack: don't leave home without it.

I suspect it's a lot like "Aviation Permatex" which is what I use. It doesn't harden either.

I like the positive feedback I'm receiving .

Come to think of it, I guess that explains what the brown gooey stuff was on the block drain plugs and freeze plugs that my machinist installed.

i've used both. all i use now is the liquid tefelon