I use a white lithium grease that has teflon in it. The can says its designed for metal to metal. So far its been fine, even on lens helicals and gives it a decent focusing feel, not as nice when the lens is new, slightly stiffer. I contemplated buying the nicer lubes, but some get really expensive for a tiny squirt tube. Wasnt worth it for me, especially when I was cleaning and lubing things that didnt cost much anyway. I also use graphite/moly powder too but not for gears, I mix it up with some naptha and apply it.