Hi, I’m trying to save some time by asking instead of searching the site for a basic answer, so thanks for answering. Is the grease used on threads and o-rings “dielectric grease”? thanks!
Dielectric grease is just a grease that doesn’t conduct hardly at all, so lockout still works if the tailcap is anodized.
Short answer: pretty much. I just use Vaseline most of the time, but nyogel is really good stuff if you have the money
I just use a Silicone grease that’s safe for o-rings. I’ve never used any on my lights that was specifically dielectric even though I keep a tube of dielectric grease handy for spark plug changes.
Practically any oil or grease is inherently dielectric anyway
I’ve often wondered if the Permatex Dielectric Tune-Up Grease they sell in those tiny tubes next to the spark plugs in the auto parts store is any different that the bigger and cheaper tubes of multipurpose silicone grease they sell in the lube section.
I thought dielectric grease was able to tolerate higher voltages without breaking down?
Yes dielectric grease tolerates higher voltages, but plain old mineral oil can handle 60kV per milimeter. The only time you’d be concerned is in something like a car ignition circuit, but even those rarely get above 30kV.
Edit: as a matter of fact, line transformers, like the big bucket things on power poles, are full of mineral oil to keep them from arcing internally between coils. residential line voltage in the US is 7kV.
That regular silicone grease is more than likely the exact same thing as the dielectric stuff too.
I’ve been using exactly that for the past few years, and haven’t had any problems or dissolved any O-rings. It’s a bit thinner than some lubes, but one of those little tubes still lasts an awful long time.
I’ve tried plumbers lube, the heavy sticky silicone stuff re-badged for flashlights by some Chinese sellers, and found it to be generally too stiff for my liking.
Using a tube of lithium grease.
Still a noob on this department and when confronted with all the different greases at the hardware store I thought it funny since the cells used are lithium ions.
In some topics I read it is good and it does not affect lockout
I appreciate all the help. I have said it in many threads and probably will again many times, “I am new with many questions and most will sound dumb” :-/ so here is another question that will either sound intelligent or illiterate:::::::::: Am I correct that the tubes threads are what completes the electrical circuit, and if so why isn’t there a lubricant to enhance conductivity instead of possibly hindering the circuit connection?
I always have on hand Permatex dielectric grease for normal auto maintenance and will gladly use it if on my lights after reading all these replies.
Thanks for helping/putting up with this! 
Depends on the anodization
If the threads are bare they conduct but in lockout lights the threads are anodized and only the edge conducts (hence how you can lockout by a little unscrewing)
I’m trying to picture which edge conducts? Please read last sentence. Thanks!
The more I research this grease thing the more research I need to do. I think grease is mainly to lubricate, with as few undesirable side-effects as possible. It’s electrical benefit and conductivity we may as well say is zero?
I’m still trying to find out the effects of anodizing. I have to say I am surprised a circuit is completed at all between the tail cap and tube, even without the further use of additional electrical insulating materials such as grease.
I am new, I am already a flashaholic, I have it under control :-/ , I am confused, I am learning, I am confused,
point the light at the ground, with the tailcap off. The bright ring around the end of the tube completes the circuit.
It’s the end of the battery tube which completes the circuit, not through the anodized threads. Pull the tailcap off and you’ll see that. Keep the grease away from the end, only the threads and O-rings need lube.
Phil
You guys have made my day and I thank you. It all makes sense, finally!!! I have been sniffing down the wrong trail and am seriously happy now knowing I can move on to the next challenges, and just one of them would be why isn’t there more interest in EDC adjustable focus lights. I love the option.
Thanks again for clearing things up!