I have recently acquired a large ceramic outdoor cooker. The top damper threads up and down to open/close. Temps inside can reach 800F, so the thread (3/4-10) needs some unusual lubrication. At the same time, you don't want anything that will drip onto the food, or dry up and flake toxic stuff onto the food.
These cookers have a recurrent problem with stuck top dampers. I am sure that some kind of anti-sieze or hi-temp grease must exist that will work.