Bill, you know as well as I do that when your backing out a threaded object and it feels lik it's dragging or is going to bind you thread it back in a couple of threads then back it out some more and continue to do this and 99% of the time it comes out without damage.

Ya just gotta have patience. So many times the hidden part of the threads get quite a build up and it has to be removed a little at a time.

I have always used antisezure compound especially when it's steal into aluminum. I think antisieze is good insurance coupled with proper torque.
Steel to steel is always good to have another compound between the two to prevent seizure.

Point. When I removed the little cap screws on my thermostat housing, they were drier than a popcorn fart and sounded lile a rifle shot when they broke free. JMHO


Rog