What's the best lubricant for endcaps?

Hi there, the title pretty much says it all. What's the best lubricant for the threads on small aluminum flashlights? Thanks!

At least that's what I use. I used to use graphite powder, but apparently some grades of aluminium react badly to it - it can cause corrosion of aluminium. Where the threads don't carry current (If they are anodised they are not intended to carry current) I have successfully used plumbers' PTFE tape - chemically inert, easily removeable, etc, etc. But also a very good insulator. It does give a lovely smooth feel though. Very fine PTFE in a light oil would probably work very well, but be horribly expensive. Allegedly hydrocarbon lubricants (Like all the light oils you can buy) can eat O rings. Nonsense I say - it is decades since O rings were made of natural rubber and silicone rubbers may sell slightly but will not be eaten by hydrocarbons. Motorcycle fork oil ought to work well, or even SAE90 gear oil though you are going to have to apply that with a stick - you can just about slice the stuff.

When I've had nothing else, I've used heatsink grease but remember it is very abrasive so don't leave it in there or use it in a twisty.

For cleaning it off I use whatever comes to hand, usually isopropyl alcohol, WD-40 or after removing any and all O rings, ethylene chloride. I have access to other, nastier solvents if I need to - my original training was in chemistry - I even have stashed in the garage a few litres of carbon tetrachloride for extreme degreasing. Only use this stuff with proper protective gear or if you don't care about getting cancer though.

I find that a very light smear of silicone grease last for a couple of years normally. If you want to get fancy, an anti-sieze paste might work - Copaslip or the like, in the UK Maplin only seem to sell lubricants in spray cans nowadays which is horribly wasteful.

This stuff ought to work well. What I use is this stuff - in a tube not a spray can. I've had the tube about 8 years now and have used about 25g/an ounce in that time.

Great, thanks very much! I have some 100% silicone for a caulk gun. I think I'll put some of that on it. As far as I know, most of my budget (cheap) lights do conduct electricity through the threads, so the plumber's tape is out of question.

Just as long as it isn't a silicone sealant - that stuff sets. If it smells like vinegar it is a sealant, not a grease. You only need a tiny amount - I wipe off more than i leave on the threads. Use something disposable to wipe it off, it tends to get everywhere if you don't. Then the ethylene chloride comes in handy.

Yikes, thanks, you are very right sir. The silicone that I have is a sealant, although it says 100% silicone on the tube... Obviously has some hardening agents mixed in there too.

I have some light oil that I always called "Sewing machine oil", I imagine that would work. Maybe I could even try some cooking oil, corn or canola couldn't be hard on an O-ring.

Though castor oil ought to work very, very well. It is an excellent lubricant even under extreme conditions. It used to be used in racing engines - it makes a wonderful smell when it burns. However, it is totally incompatible with mineral oils as it forms a nasty gritty mess in contact with them so clean any previous lube out very, very thoroughly.

Corn oil would become rancid and very nasty rather quickly.

Sewing machine oil should be just fine. Best way to apply is to put a small amount onto a cloth and rub it over the threads. Then wipe much of it off with a dry cloth. Toilet paper works very well for this. Any new engine oil should be fine - I'd go for thicker stuff myself - it is less likely to come out all over hands and clothing.

DO NOT use engine oil that has been used in an engine - there are lots of nasty things in it - contact dermatitis is not unusual with it and there are a lot of strongly carcinogenic substances in it. Wear impervious gloves when handling used engine oil.

Great, thanks for your expertise Don.

I knew all those chemistry exams I failed would have to come in handy sometime - well, i eventually passed them all, just rarely on the first try...

i use a little smear of petroleum jelly i use it on all of my lights have done for years with no problems

although some will say its not the best thing to use its worked fine for me cheap easy to get

it dose dry up a bit on lights that get hot i just wipe clean with a cloth and reapply as required every few months or so

cooking oil will go sticky i have tryed it and it is not easy to clean off

Barrie

A yes, Vasoline type stuff would be good too.

I've put Copaslip on all of mine..

Doesn't that get awful messy? Or maybe I always use far too much of it.

no i just applied a very small amount with a cotton wall bud I used that to work it in to the thread then reapplied screw cap opened and closed a few times and the wiped off excess. finally cleaned the rest of the light with IMS

I use RC grade silicon grease......works well.

I use 90% pure silicone grease from Ace Hardware. Used sparingly, it works very well.

Thanks for your tips!

I guess the consensus for o-rings and lube is silicone.....i know they make better stuff but for me its more like use what you have, and if it works then keep on using it right.

Sorry for resurrecting an old thread, I hope I haven’t broken any forum rules on whether this is acceptable or not.

Anyway I trust you are all well and enjoying your weekend.

I already have cans of silicone spray which I have used on my flashlights that seems to work great but obviously with it containing solvent, it has a lasting odour.

I was thinking of getting a tube of silicone grease like the stuff in the link Don kindly posted but before I do could anyone who uses the tubes please tell me if it has a strong smell?

Thanks,

Gary

The one that i use which is a small shot kind of tube works well and there seems to be no odor at all coming from it.

I don't notice any smell at all from the Maplin stuff but then I do smoke 40 a day. Despite that, I do have a rather acute sense of smell. An alternative is Copaslip which also has no smell that I notice - available from your local motor factor anywhere. Most of the spray lubricants will wash out any useful lubrication - avoid WD-40 like the plague. Though I do like the smell of it when it burns, spraying it on exhaust headers makes a nice smell.