What should I use as a thread sealer for V6 head bolts? Fel Pro recommends a teflon sealant, probably because it's a better lubricant. I suppose another option would be Permatex #2, which makes some strong claims, like like up to 400 degrees, resists glycol, etc. I just want to use the right stuff since I only want to do this job once!

I always use teflon tape on stuff. It resists everything I can think of. It's used in every kind of plumbing but gas lines.

((You can't use it in natural gas and propane, that sort of thing, because it interferes with electrical continuity on the pipes. Bad grounding on such pipe makes for big boom noises and very short buildings.))

Loctite PST. Try it once and you'll throw the teflon tape away.

What's the point of thread sealer on head bolts? Does it just prevent loosening over time?

yobtah asked: What's the point of thread sealer on head bolts? Does it just prevent loosening over time?

The head bolts are not in blind holes, they enter into the water jacket; therefore, the sealer keeps coolant from seeping up around the bolt threads and into places which it doesn't belong.

But I've always wondered what potential the lubricating properties of the sealant might have on bolt torque readings.

I've always used high temp RTV with no problems.

Even on the bolts you don't teflon you are suposed to oil the threads. Main thing is not to use to much teflon and cause the bolt to be to tight in the threads to start with.

I don't know how the PST sealant is, I haven't used that one. I guess it depends what state the block is in what sealer to use. I've had allot of trouble with sealers unless the block is clean and dry like durring a total rebuild. If the block is wet I think I'd still stay with teflon tape. It doesn't care about wet threads.