Used vaseline before, then ordered some inexpensive silicon grease (unknown brand, AE or BG) which was too viscous for threads. Now I have a jar from Mountain Electronics which works great.
I bought a 3 ounce tube of Super Lube like 8 years ago, I barely made a dent in it, probably last me another 8 years, talk about getting your money’s worth
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Does anyone of you used these?
Cheap food-safe grade silicone grease. Works great to lubricate o-rings, not so much for threads because of the low viscosity.
I use Super Lube Multi-Purpose Synthetic Grease (that I got from Harbor Freight). Super Lube makes different types of greases so you have to be careful which one you use for flashlights.
The “Multi-Purpose Synthetic Grease” is compatible with both nitrile and silicone rubber, which I believe is the material used for the O-rings in flashlights. The black O-rings are usually nitrile and the clear and color O-rings are silicone.
But the Super Lube “Silicone Lubricating Grease” is not compatible with silicone rubber. Even the Super Lube “Silicone O-ring” grease is not compatible with silicone rubber.
That one is super in every aspect, price included. Bought one years ago at FastTech, from this $2.61 listing; they also have it listed at $3.15, guess they messed up.
Am I the odd one who use Permatex Dielectric Grease on my lights?
Superlube has worked wonderfully for me and is available locally
.
I will give it a try, my lights are dry and need lube. 
I use RICO Cork Grease, it`s for clarinets and saxaphones etc… it comes in a tube just like chapstick and works great!
i bought some silicone lube at a dive shop prbly 10 years ago, i figured if it was good for divers, it is good enough for flashlights.
Well if you had some laying around then go ahead. I would still go with any form of silicone lube over dielectric grease.
I find that dielectric grease is sticky that’s why I use them especially on my keychain twisties. As for any different from silicone lube, I think it’s more economical to use silicone lube plus it moisturizes your o-rings
I use the Ford Motorcraft XG12 dielectric grease thats Nyogel 760G. Good lubricant for O rings and threads? - #19 by RobertB
Not sure what the permatrex makeup is but it could be close to the same.
The XG12 was much cheaper than buying the retail labeled 760G grease.
It was sold on BLF at one time. SOLD OUT! -- thank you -- 3 ounces of Nyogel 760G for $12, postage included -- U.S. only
I got some Yezl SG6 from fasttech. Took ages to come and corona made it even longer but it works.
I use TEF-GEL on flashlights and our boat. It is a ptfe based substance that has no electrical conduction, never dries out, won’t wash away with moisture, and only needs one application. I think it was primarily developed for the marine industry. It’s expensive, but a two ounce tub will last quite awhile, and won’t go bad at room temperature, at least so far. My tub is eight years old and it’s about a third gone. It’s super sticky and will make a mess of things if not careful. I put some of it, along with some silicone on a piece of metal and left it in the sun for a few weeks. No discernible change to the gel. The silicone was gone however.
Years ago I was using silicone based grease for o-rings and such, but had to re-apply every year or so. After awhile I noticed black on my fingers from seals degrading, probably from not applying often enough. I was using silicone grease designed for seals and grommets. Silicone dries out and disappears eventually, as do most other seal treatments I’ve used. TEF-GEL was designed to prevent corrosion between dissimilar metals in contact with each other, but it works fine for seals. Anyway, no more black fingers and I only have to do the job once, as it never dries out. And, threaded parts disassemble with ease. Don’t get me wrong. If I put it back tight it stays that way, but won’t gall or lock up from corrosion. Best to clean surfaces first to remove the old lubricant.
Hey, Nyogel was like the past favorites for CPF and it’s super difficult to find for me in Malaysia. I’m not sure how they perform but I stick to Permatex because of the viscosity. I tried some local brand dielectric grease and they’re very smooth Vaseline texture while the permatex had a sticky glue like texture for a grease which makes me always fall back to it. Very useful on holding twisty lights as they won’t fall off.
Totally user preference here
I use Trident silicon grease… same as for my SCUBA equipment
Nope. 
I finally used up my Ford tube. Back to using the 760G tube that's about 1/2 empty I bought from Battery Junction way back: https://www.batteryjunction.com/nyogel-760g.html.
I did recently buy a tube of SuperLube w/PTFE as TK recommended recently, bought here: https://www.amazon.com/gp/product/B0081JE0OO/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
This stuff can go quicker when lubing up a few BLF GT's and other large lights.