During my Navy days working on the flight deck of carriers, while putting the steam catapults back together, we used a metric ton of anti-seize. The copper or nickel would remain on the threads long after the oil and grease would burn off. The softer metal would act as a lubricant when it was time to tear apart the equipment allowing the bolts break loose. While the extreme temperatures and salt water would still rust the crap out of the bolts, we were able to get 90% of the bolts apart. This practice has remained with me and when I put my engine back together there would be a good bit of smoke burning off of the bolts from the anti-seize after I started the car.
As for the plugs, I use die electric on the threads. Hasn't done any harm so far.
