WD-40 (WD stands for Water Displacement) is a penetrating oil, not a lubricant. It works great to get things that are stuck moving again, but does not provide lasting lubrication. Top Coat or similar products would be better. If you lube at all, you would want a product that dries thoroughly and will not attract dust.
BTW, I have never lubed my OF1400 and the other day (after 3 years use) I noticed a little corrosion on the posts. That really surprised me as I live in the desert, usually less than 10% humidity - things just don't rust out here....