I was going to change out my plugs and also keep an extra on hand in case I need it. Anything special I need to be aware of? In the cowling they state which NGK plug and then I believe I read tighten to 18nm. My current plugs have some corrosion and there is some salt spray under the cowling with slight rust on a bolt or two.. I was going to change plugs, rinse salt off then use Corrosion Block under the cowling. opinions?