never seize is good on nearly every threaded connection. Spark plugs included. I have worked on ships for 20 years, fishing up in Alaska for 15, and now I work at a waste water plant. We go through never seize like candy. Use it on many of the gasketed joints as well. That way you don't have to worry about scraping the gasket the next time you take it easily apart, because you used never seize on the bolts too. Up in alaska we would take bolts out of new machinery one at a time to put never seize on them so when we went to take it apart 5-10 years down the road it would. (come apart) It also works really good on battery connections, it is very conductive, helps prevent corrosion, and the bolts don't seize up.
