Head bolts - sealant or no sealant?

[rjkoop]

I've read a few conflicting things for installing the head bolts/studs. I'm going to clean out the threads in the bolt holes and dip the threads of the studs in oil based on what I've read. Do the studs need some sort of sealant (teflon) on them as well? I've got the studs/nuts instead of bolts. Should I apply to both ends? Some of these bolts go into water passages and I want to ensure no leakage.