Even though the threads are plated, oxidation still occurs because of the dissimilar metals being together. I've removed threads from rotor housings when removing old spark plugs on customer cars. I have always used a very thin coating of grease on the threads on the spark plugs and have never had an issue with seized spark plugs or spark plugs that were over torqued.

That's not to say that someone that's not being careful cannot over torque them and the grease can contribute to over torquing on nuts and bolts. But I use it on every restoration I do and I am cognizant of it and am careful in my application of torque values. Maybe it's just an Ohio thing, but it helps a lot.

 

Well, since we're on the topic, I think that's a good idea if you don't DD your 8.

If it's your primary DD and you do 35K or less tuneups, it's not necessary, but, if they sit for long periods of time, I would use it, which I will on the LY soon as she'll be getting some work done soon.