Here is a link to the Lippert Level-Up Operation and Service Manual.
Scroll down to the chapter on Preventative Maintenance Procedures.
See where it reads that you should use Silicone on the Jacks.
For those who think is reads that you should use WD-40 on the Jacks you might want to re-read it.
For discussion purposes, WD-40 will certainly help prevent corrosion/pitting on the aluminum Jacks. So will cosmoline. The problem is that WD-40 is not good for the bottom seal due to its composition. So for those using WD-40, you will probably not have leaks from pitting. The leaks will be from a deteriorated seal.
Time will tell.
38FLCamper brings up a good point about condensation if you wrap the gear in plastic. I should have been clearer. I did not SEAL the bags. There was plenty of ventilation to prevent condensation. The bags only prevented blowing sand, ice pellets, snow and other airborne debris from beating against the exposed aluminum. Thanks for bringing that up.