i think on all cars they can arch. I use it to prevent it. They come in little pouches at the checkout counter and a pouch is only like .99 cents. it has enough grease to do like 3-4 spark plug changes. just put a little grease on the inside of the boot or right on top of the spark plug where the boot go's over it.

But putting this grease on the plugs might not help with that other arch problem you are having, but putting the grease on the plugs is still a good idea.