'Twisty' lights with bare aluminum threads (like the old Jetbeam C-LE v1.0 and v1.2), are the most critical. The wrong lubricant will not only make for rough operation, it can cause excessive thread wear leading to early failure.
Here is a wrapup of some common lubricants and their applications:
Krytox
Krytox is hideously expensive (a 2 oz tube of Loctite Krytox will set you back about 40 dollars), but it is exceptional at reducing galling in stainless steel and Titanium. It will also completely eliminate o-ring sticking. Not for use on bare aluminum threads or lightly anodized surfaces because it is abrasive to these surfaces and will lead to excessive wear. I use Krytox with my little L0D-Q4. The L0D has hard type III anodized threads which do not grind or wear with Krytox. The decision to go with Krytox over Nyogel 760G in the L0D was based on the need to eliminate o-ring sticking. My L0D has a very tight o-ring which was having sticking problems with every other lubricant that I tried. With Krytox, my L0D now has perfetly smooth one handed operation. BUT REMEMBER KRYTOX IS NOT FOR LIGHTS LIKE THE C-LE, WHICH HAVE BARE ALUMINUM THREADS. In the C-LE, it was NOT smooth at all, and eventually caused enough wear to lead to thread failure.
Nyogel 760G
A synthetic silicone based grease, but much smoother and lower wear than other silicone greases like silicone plumber's grease or Dow Molykote 111. Nyogel helps to minimize thread wear, even in soft alloys of bare aluminum, and shows only slight o-ring sticking with tight o-rings. It's a good choice for Twisty lights with bare threads like the Jetbeam C-LE. Overall Nyogel is a fantastic general purpose grease to have around, and you can get a
large 2 oz tube from battery junction for just over $10 shipped (if you use the lowest cost USPS shipping option).
Moble 1 Automotive Grease
Moble 1 Automotive Grease works a LOT better than you might expect. This grease actually gives smoother operation than Nyogel 760G in my C-LE, and I have had no problems at all with o-ring sticking or deterioration (even after several months of use). Other general purpose Lithium Greases may also work, but some have expressed concerns that greases with volatile components might release vapors that could fog your flashlight's main lens. I haven't had any problems with this while using Mobil 1 Grease, but anyone who is concerned should stay with Nyogel 760G which is fairly close in performance and is known to have very low volatility.
Dow Molykote 111 or Generic Silicone Plumber's Grease
Poor lubricant properties and heavy o-ring sticking (o-rings will almost weld if the light is left unused for a few weeks). Not Recommended.
Tetra Lube G (or other PTFE or Teflon based grease)
These greases are a fraction of the cost of Krytox, and work just as well at providing effective lubrication, but are not quite as effective at eliminating o-ring sticking. In my testing, these greases were slightly less abrasive to bare aluminum threads than Krytox, but I still would not recommended them for lights like the Jetbeam C-LE (or any other twisty lights which use bare aluminum threads).
