I Waxoyled it because many areas on the Golf V don't seem to have any rust protection at all. Remove the undertray, or any of the wheel arch liners, and there is zippo there - just a basecoat of paint. Now, bearing in mind when I posted about the rust trap in the rear wheel arches (thread on the other side - went down with the sinking of the Titanic!
), I reckon prevention is always better than cure when it comes to corrosion.
Even the box sections didn't have any!