Good lubricant for O rings and threads?

I have tried Krytox and Dielectric grease. On large diameter lights, it is difficult to move the tail cap or battery tube because it is tight.
The best thing i found is sewing machine oil, applied very lightly or dry, no lube.

https://www.amazon.com/dp/B0006O5GHW/

I use this for my rc and lights.

WD-40 means it is a Water Displacement formula discovered on the inventors' 40th try. It is not an "oil" as many believe. It is an extremely thin petroleum distillate product and dries out very easily without leaving any worthwhile residue to maintain a good lubricant quality on the parts that were sprayed. If anything it tends to attract dirt/dust, evaporates, and then nothing is left but the dirt. Any real oil, including sewing machine oil, is much better at providing lasting lubrication compared to WD-40. And as mentioned above WD-40 can work to soften or dissolve certain rubber parts like o-rings.

Here's what I use that will not wash off with water, is long lasting, and won't harm your flashlight o-rings:

https://www.amazon.com/Super-Lube-93003-Silicone-Translucent/dp/B07CFS31M8/ref=sr_1_1_mod_primary_new?crid=2BUBBYHUJ3LK5&dchild=1&keywords=super+lube+o-ring+grease&qid=1622692792&sbo=RZvfv%2F%2FHxDF%2BO5021pAnSA%3D%3D&sprefix=super+lube+o-ring%2Ctoys-and-games%2C181&sr=8-1

It is not expensive, can be found at hardware stores, automotive parts stores, and online. The 3 oz tube will last a very long time.

.

I bought a 3oz tube of Permatex 22058 Dielectric Tune-Up Grease for spark plug boots years ago (and I expect I’ll be able to pass it down to my theoretical grandchildren someday at the rate I’m using it) and it seems to work quite nicely. It’s silicone based and has worked for me, so far. Also great for my pocket knife (a Kershaw Blur; I use it in the pivot as well as in the recessed spring ‘well’ inside the handle).

Unfortunately, Super Lube 93003 Silicone O-Ring grease is not compatible with silicone rubber according to their website (Super Lube Silicone O-Ring Grease ), which is used in a lot of flashlight O-rings.

Instead, I would recommend Super Lube® Multi-Purpose Synthetic Grease which is compatible with silicone rubber O-rings.

We lubricate o rings so they last longer. What would you do if you found out that o rings would last longer of you did not lubricate them?

I use synthetic grease for o-rings.

Too much is worse than too little.

tbh, I think grease is way too thick for a flashlights threads given that test show too much is worse than none, you are 100% guaranteed to get too much, and cleaning off the excess is nearly impossible, i sadly followed some advice in here…… do not buy the super lube grease. if you do, take the orings off and make sure it’s not globbed on.

Hornady one shot is guaranteed to go on thin but it’s a waste to use it on flashlights, just use a thinner lube and try to dry it off, the remnant is enough

There seems to be some conflicting info on silicon o-ring lube compatibility, and I am confused too, LOL.
Do we have any Chemical Engineers or Experts here at BLF that can clear this up ?
I found this and it looks wrong too. :weary:
.
https://www.parker.com/Literature/O-Ring%20Division%20Literature/ORD%205700.pdf
.
2.2.13 Silicone Rubber (Q, MQ, VMQ, PVMQ)
Silicones have good ozone and weather resistance as well as good insulating and physiologically neutral properties.
However, silicone elastomers as a group, have relatively low tensile strength, poor tear strength and little wear resistance.
.
Heat resistance
•Up to approximately 204°C (400°F) special
compounds up to 260°C (500°F).
.
Cold flexibility
•Down to approximately –54°C (–65°F) special
compounds down to –115°C (–175°F).
.
Chemical resistance
•Animal and vegetable oil and grease.
•High molecular weight chlorinated aromatic
hydrocarbons (including flame-resistant insulators, and coolant for transformers).
•Moderate water resistance.
•Diluted salt solutions.
•Ozone, aging and weather.
.
Not compatible with:
•Superheated water steam over 121°C (250°F).
•Acids and alkalis.
•Low molecular weight chlorinated hydrocarbons
(trichloroethylene).
•Hydrocarbon based fuels.
•Aromatic hydrocarbons (benzene, toluene).
•Low molecular weight silicone oils.
.

as an example, Page Not Found | Super Lube

Synthetic grease is basically artificially made vaseline without the big silica granules in it… and is considered “good compatibility” with silicone

I’m pretty sure very few if any flashlight orings use “natural rubber” and real silicone lube will blow up silicone rings so bad you will not be able to take the light apart… which leads me to believe most are also not using silicone

Responsible manufacturers would say what the orings are made of, and their dimensions…that being said, I think most of them use more overall compatible formulations.

Well, once upon a time, long long ago, I worked as a Chemical Engineer and had to use a slide rule to figure things out. Note, digital calculators and computers were not invented yet. For arithmetic we got to use pencil and paper since these were invented after chisel and stone.

I do remember a few things such as: O-ring selection is based on chemical compatibility, application temperature, sealing pressure, lubrication requirements, quality, quantity, and cost. Some typical O-ring materials are: Nitrile (Buna-N), Silicone, Fluorocarbon (Viton), Perfluoroelastomer (Kalrez®), Fluorosilicone, Ethylene Propylene (EPM, EPDM, EP, EPR), Neoprene, and Polyurethane.

Use of silicone o-rings is for static applications where they will be put in place and not messed with since silicone is relatively soft and subject to tear easily (silicone has poor tear and abrasion resistance and should only really be considered for static rather than dynamic applications). Therefore it's application for threaded connections is not recommended, i.e. flashlight threads. It is also more expensive than a typical synthetic rubber o-ring such as Buna-N, EPDM, or Viton, and over the production of 1000s of flashlights it is unlikely for a manufacturer to utilize a silicone o-ring in their flashlights due to relatively high cost alone.

I do not know of any of my flashlights that have silicone o-rings. If you have a flashlight (unicorn) with silicone o-rings that's great, then don't use a silicone based grease on them. If your flashlights are like mine, then super-lube with or without PTFE (or any equivalent) is fine as a thread and o-ring lube.

.

I’m a diver that does their own regulator servicing. I have Buna, Viton, EDPM, and silicone O-rings. Silicone is almost exclusively in underwater camera static application, usually coming with their own specified lube.
So, I’m not to too dense about O-rings. I don’t KNOW what are in most flashlights since they never come with specs of that sort, but they ‘seem’ to be primarily silicone; semi-transparent, soft, stretchy. They are far more like the camera O-rings than anything else I work with.

Like dissolves like, though silicone seems to absorb, get fat and mushy. So, know what you lube is made of. Take your best guess on the O-ring.
For a flashlight that is not exclusively designed for diving or wet use, probably doesn’t matter a lot as it seems a number of people are getting along fine using an inappropriate lube successfully.
For my ‘dry’ lights I often simply remove the damn things as they serve no real purpose other than annoyance.

I have to humbly disagree with your statement that the o-rings on most flashlights ‘seem’ to be primarily silicone - The only o-ring on my flashlights that ‘seems’ to be semi-transparent, soft, and stretchy is the sealing o-ring under the lens. It is the only one that ‘might’ be silicone but it’s doubtful. The o-rings on the top and bottom of the battery tube are solid black, fairly firm, and not very stretchy. And yes I do know that silicone comes in a wide variety of durometers (firmness). Without lab analysis I’d guess these o-rings are Buna or EPDM.
We do have something in common - diving. Although my scuba diving was simply sport diving and not pro like you seem to be. Besides, back in those days silicone was mainly known for breast augmentation.

To be fair, all the orings I have feel a lot like my thick, uncoated nitrile gloves…that stuff is compatible with nearly everything, and it can stretch a bit.

well, I haven’t felt the viton oring in my sprayer and I’ll refrain from that unless it looks like it’s going to fail

I think SIGShooter makes valid points. In the big scheme of things it makes little difference what brand one uses. This is not Rocket Science & no point in trying to reinvent the wheel or overthink it. :wink:

Yes, Silicon lube IS NOT good for Silicon O-rings. BUT… how many Flashlights actually come with Silicon O-rings??

I have a TON of lights & I can’t name one off the top of my head, can you???

I have been using SuperLube Synthetic Grease (Multi-purpose I think) for over 20 years on my light threads & O-rings with NO problems at all.
I have never ever had an O-ring to swell.

Here is what works “for me”. YMMV…

1. Get a three (3) ounce tube of SuperLube.

2. Buy a syringe & the largest gauge (boggest bore) needle you can get.

3. Remove plunger from syringe & fill with SuperLube. Carefully replace plunger.

4. I then blunt the point on the needle to avoid stabbing myself.

5. The result is a very easy way to despense the SuperLube. It can be used with or without the needle.

The needle comes in handy for tight places. Especially in fishing reels, knives, & guns.

This is what works for me & has for over 2 decades. :white_check_mark:

scientifically speaking, frog lube/one shot/other ptfe products are best.

but these are really overkill for a flashlight…doesn’t matter what you use as long as it’s not globbed on

Do this allow mechanical lockout? I have to try this. :open_mouth:

These are the O-rings used in Convoy flashlights (which I have plenty of): 21*1.5mm black silicone O-ring for flashlight.

Or these from Kaidomain: 20MM X 17MM X 1.5MM WATER-TIGHT O-RING SEALS - BLACK ( 5 PCS ).

I know the title or description uses “silicone”, but are the black ones actually silicone? They seem like it to me. I have some that have been slightly sliced when I got the Kaidomain hosts since they were not properly lubed.

I work it into the grooves with my index finger. Not high tech but you get a lot of control.

Thank You everyone for clearing this up for me :smiley: , I have tried several lubes and now I feel comfortable using Super Lube.
I just ordered :
Super Lube 51004 Synthetic Oil with PTFE, High Viscosity, 4 oz Bottle,Translucent white.
I will also get a syringe and needle to apply it with.
:beer:
.