Cleaning gritty threads (redux)

I finally got some silicone (plumbers) lube and I've cleaned and lubed all of my lights. They all feel silky now, EXCEPT my Fenix P2D head (non-anodized) threads. They feel smooth until it's almost screwed all the way down, then it 'grinds', then when I unscrew/screw it back, it feels awful.

I've read a few threads, here's what I summarized: Don't use cheap paper like toilet paper or paper towels, they leave fibres. Guilty! So I cleaned it very well with a q-tip and isopropyl alcohol. Cleaned until nothing else came off, then carefully re-lube the o-ring, put it back on, and lightly put some silicone grease back on the threads. Exactly the same as before. :-/

I've read that silicone grease is too heavy for aluminum threads, so next order from Fenix-Store I'll get some Deoxit as 47s highly recommends it.

Any other suggestions to try in the meanwhile? Not like I turn the head much, but it feels really awful right now. I might try vegetable oil on it, but I've read that it breaks down and gets goopy and that it causes higher resistance causing significantly lower runtimes (Chevrofreak mentioned it once).

You need some Krytox to make those threads silky smooth. Check out the link in my sig for details. This stuff works especially well on the Ti lights also not to mention that it is safe for all o-rings.

I'd try something thicker- I used rather light silicone spray lubricant on my L1D and all was good, but did the same to my Arc-P and it felt like the head was full of sand! Wiped the stuff off, used some Castrol multipurpose grease (also good for wheel bearings) and now it's fine.

Silicone is fine for the threads. I don't know where you got that it is too thick because the thicker the better. I doubt that you need higher viscosity unless you were threading the tailcap on at high rpms for some odd reason. Also, silicone is a lot cleaner and doesn't have a bad smell like bearing grease.

I have over 50 lights, and I have switched completely over to St. Claire's NanoLube Oil. I previously used Nyogel & silicone grease. I use those "Lint Free Cloths" sold at Staples for cleaning a computer monitor/TV screen to clean the old gunk off the threads. No more gray discoloration.

Interesting, I read a thread when doing some initial research that said that silicone grease was too thick for threads, but good for orings.

So I guess the grease is okay, perhaps I'll try a microfibre cloth. Don't have any extra laying around, what I do have is packed in camera bags etc and I'm definately not going to use them. ;-)

I have not had great success with silicone in my Peak Pacific's threads - for some reason it just wouldn't lubricate fully despite numerous applications. I finally used a teflon lubricant - sprayed on a qtip and applied and it has worked great. It's basically the spray version of SuperLube which is, IIRC, what Doug at the old flashlightreviews.com used on all his lights (but he used the tube version).