I fly my 250 quad in the winter and use Corrosion X to lubricate my motors and water proof the electronics. Flite Test did a show on Corrosion X awhile back pretty impressive stuff it is all I use now and not only for RC stuff.
Interesting this subject came up I was just talking to some others on another forum about lubrication, ATF came up but I feel it would attract dust/dirt, and also Boca Bearing High Speed oil. I am going to try the CorrosionX.