I use an automotive wax to protect the chrome after cleaning/de-rusting. While WD-40 provides some protection, it doesn't seem to last more than a few weeks. Automotive wax will also need to be reapplied. My opinion is that the wax lasts longer than WD-40.

I am also waxing many of my tools now, rather than oiling. How long the wax last depends upon conditions of storage and use. I figure that in my garage, maybe a year?