My experience with Vaseline (coating battery terminals on my car) is that it runs like the devil. Something you want when water/acid-proofing terminals and stranded wire, but something I would think you don't want when dealing with lenses. I would opt for some hi-tech silicone grease that stays where you put it. Shouldn't cost a fortune, if you look at an industrial supply company instead of some specialist optics supply place.
Originally Posted by David Lyga