I was wrong.
Somebody did lab test what’s in WD40 here.
Thanks guys for info. Now figuring out which one to use that is cost prohibitive and easy to acquire.
Well. living in the moist pacific northwest, iffn you decide on the snail/slug option, I can offer volume discounts.
my favorite food at xmass !!
That one of those ‘it depends’ questions. I’ve replaced some of the O-rings in Chinese dive lights I get before I took them on a dive. I’ve had other O-rings that I’ve used for years and they seem to be fine.
Generally O-rings are [static=no movement] or [dynamic=movement]. Static can last for years. Their most common problem is permanent deformation if they end up being kind of a “sealing washer/smashed”. That’s not hard to see and those get replaced.
Most of the ones in lights are [static], get compressed to seal, but don’t get smashed. With PROPER lube (non-destructive) those can last for a really long time, IF they are decent material in the first place. Not all O-rings are created equal and some of the ones I’ve gotten on cheap lights are kind of suspicious. But, water-resistant to rain and such is simply not the same as 60 feet of water pressure.
Dynamic O-rings are under constant movement (hydraulics, some parts in dive regulators). Those are subject to pressure and wear. In regulators they are recommended to be replaced annually. But, a LOT of that is liability, and pure fear driven capitalism. I’ve overhauled 20 year old regulators, simply cleaned and lubed what was there, replaced nothing, and bet my life on it by diving it. I absolutely test them for performance and leaks, but more often than not they work fine.
Camera case manufactures recommend annual replacement of their O-rings. But, it is time consuming to send them back, and quite costly. OTOH, a failure of one can immediately destroy $$$$ worth of electronics. But, the harsh reality is it’s usually NOT an O-ring failure, it’s something the operator did wrong. So, I’ve overhauled cases myself, but I’ve never sent one it. I absolutely try to keep the compression off if possible when not being used.
Long way of saying, keep them clean, use the right lube, and they’ll last for years.
Permatex Dielectric Grease (made for spark plug boots and battery terminals) has worked for me for years as a budget silicone grease and it’s never caused harm to any of my o-rings, but as stated who knows what they are made of.
I got some Oatey silicone plumbers grease which is supposed to be almost pure but it’s not thick enough for me.
I’ve used Slip 2000 EWG (grease) in a pinch.
BTW, i’ve put different types of o-rings in seperate ziploc bags, saturated each with these lubes and left them for 2+ years (still in there actually), and cant tell a difference between them and the control samples stored in the open at room temp. The only o-rings i have in the bags that i am certain of the type is Viton for what it’s worth. The others…who knows what they’re made of.
Tidbit: The dielectric grease is also good for light bulb sockets, super thin layer on the bulb threads helps prevent seizing :+1: !
Get some Dow Corning high vacuum grease. It is made for this type of stuff. I put some in my Zephal HP bicycle pump and it went from 120 psi to more than 160 PSI. I actually cracked a rim testing the limits of the pump. I can’t see there is anything in a flashlight that is not in the pump. That is aluminum and O rings. About $20 for a half ounce tube.
Electricity 
Some lights have bare threads through which the current must flow.
Dielectric Grease all the way! It waterproofs and insulates electrical connections. It’s safe for the O-rings too.
On CPF, I had read that Mobil 1 synthetic red grease in the grease gun tube worked well. I bought some for my lights and for repacking bicycle bearings and it’s worked very well. It has a strange smell but once the light is screwed together, it wasn’t noticeable.
Same here. It’s kind of pricey but I’ve been using the same tube since about 2007 on numerous lights. A little bit goes a long way. Great stuff.
2012 here and I still have a lot left.
I may even try and repack my SWM V11R with it!
Chris
I think I got mine around the same time, Can’t even hardly tell I have used any. I got a Lifetime Supply I guess.
It probably work in the V11R, might make it less resistive to turn.
Sil-glyde too. Always used it on my caliper slider pins and now on my flashlights.
I’m amazed no one’s linked CPF’s thread on the matter. It’s very comprehensive.
I use Super Lube on everything.
Thanks, might get a tube never tried it before.
Nitecore Silicon Lube.
Liteflux Silicone Lube. Enough for the next years… 