I have been using WD40 on various metal surfaces for over 30 years (including every hinge and drawer runner in my home) and have never ONCE had an adverse reaction. And that AP900 shaft was treated shortly after I received the mount in 2007; no deterioration at all.
Not trying to be argumentative, only recounting MY experience.
Brian
PS: My neighbor is a remodeling contractor. He routinely uses WD40 on a major investment; his tools.
