There’s a lot of information out there on helicoid greases. Much of it is conflicting.
In general, a good helicoid grease should
- Lubricate with appropriate resistance
- Separate into oil and solids as little as possible
- Outgas as little as possible
I’ve settled on 4 greases. Which to use when comes with some experience, and how you prefer the resistance of your helicoids. All of these greases should be used very sparingly – any excess will leak out and migrate around your lens.
By the way, I’ve never used oils on a lens, and can’t think of a time when I would. Grease should be applied very sparingly on the helicoids, obviously, but also on surfaces which slide against each other, like aperture ring or helicoid keys.
Helimax XP
Somewhat heavy oil, works well for lubricating surfaces that rub against each other. For larger helicoids it’s often too stiff, so look to one of the lighter greases, like Molykote EM-30L or JHT #10
Molykote EM-30L
I’ve never seen this grease separate, even after a year of sitting in the jar. The weight is a little lighter than the Helimax XP and the JHT #30. Overall this is my favorite grease, unless I need something very light, in which case I use the JPT #10.
Japan Hobby Tools #10
Like JHT #10, this grease does tend to separate, but has a nice light feel. If you use it very sparingly, it might be OK, as long as you don’t leave it sitting somewhere hot, which will speed up the separation.
Japan Hobby Tools #30
A little softer than the Helimax but stiffer than the EM-30L and JHT #10. Like the JHT #10 it will separate more than the other choices on this list, so use with caution.
Liquid Moly LM 47
I haven’t actully used this one, but some repairers seem to like it. I’ve kept away from it because it’s very grey and seems like it’d make a mess. I’m also not sure how it outgasses.
Steven Kasapi 