The final cut of the 9th episode of the Tesla Motors Club Podcast, featuring Chad Schwitters, the former president of Plug In America, is now available. You can watch it now on YouTube or listen to it on all major podcast networks.
I used white lithium grease and it totally eliminated the squeak with (~ 3 months so far) no bad side effects. I sprayed it on a piece of string and then used it like dental floss between the moving and stationary part of the folding axis. Back story: after I broke the plastic pieces of my driver's mirror (purely cosmetic) backing it out of the garage, I replaced the entire unit with one that I bought on ebay - the ebay mirror was fully functional and cosmetically perfect but it squeaked.
I was worried that silicon spray could migrate and harm the paint.