I used to be on a vintage VW bus owners forum, and the more knowledgeable folks there said to never use WD-40 as a lubricant, because it is not actually a lubricant. It's a penetrant, and good for that use, but it does not work well as a long-term lubricant. They also noted that it can actually tend to facilitate future rusting. Curly/s advice to use it sparingly and apply it carefully is good advice. Make sure you can wipe it off, and if you feel you need to do any lubrication after that, I would recommend the dry teflon-based lube that others have mentioned.
Rich K.