I agree, don't be chasing any threads with the head on the block, the chips(some of them) will go right down into the cylinder, been a machinist for 24 years,JR........

 

I have used anti-seize on three plug changes and never had a loose plug. I figure I've got enough around the threads to last me a while so I haven't put any on the last 3 or 4 times. I believe my threads have been chased enough.

Here is a pic with silver anti-seize on the SF10D for the person that thought we have 8 threads holding the plug in.