You can use any grease you want. Molyben would work, white lithium spray in a can, I don't suggest wd-40 since that is more of a lube, I don't know how it would react with the plastic clips, rubber, or window tints either.
PS, I forgot to circle that extra bolt. The rear piece is 2 bolts, not 1. If you look at the attachment of the regulator removed, you can clearly see the 2 bolts, but you probably figured that out by now
