Lithium grease.

Petroleum oils aren't really good for hinges (which I assume is what is squeaking) for a variety of reasons. If you use wd-40, you find that the squeak goes away and quickly returns, sometimes worse. The reason for this is that WD-40 will wash out any grease or oil in the hinge as well as attract whatever dirt or dust is around, both worsening the squeak.

3-in-1 (in the dropper can) is a good, effective lubricant but it has an important drawback that is shares with WD-40, it will wash out any grease already in there as well as attract dirt. 3-in-1 (tin dropper bottle) is great for light mechanical duty like a bike chain or as cutting oil and even some gears, but it wont work well as a deck lube, way oil, or hinge grease because of its very light weight.

Here's a brand and type that I recommend for doors. CRC is an excellent source of this type of chemical, and my personal go-to. https://www.crcindustries.com/white-lithium-grease-10-wt-oz-...

Lithium grease (sometimes called White Grease) is excellent for door hinges because it is dry, wont drop, will spread instead of being pushed out like oil (even 3-in-one), and lasts forever. Since its pretty dang thick and not really a liquid even in the spray version, it also wont drip onto your carpet as readily while you apply it. Get the spray version, protect the paint behind the hinge with a towel or a piece of printer paper(TIP: Cut the paper %85 of the way in half long-way (hotdog fold) and slide the paper over the hinge as you spray it with the door closed and from a bit of an angle, pay more attention to the top part, just under the head of the hinge pin. That should be more than enough. Spray-on oil would soak the paper, lithium grease won't so this is another benefit of lithium)) and give it a couple squirts while working the door. Wipe the excess off and enjoy years of squeak-free operation!

It is perfect for light-duty applications where the lube sticking to its lubricating point is important. White Lithium Grease is [Edit, its Lithium soap? whatever that is.] and mineral oil, sticks to metal excellent, and is compatible with almost all bushing rubber.

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More (Gratuitous) Suggestions from the WD-40© Corporation:

Use Lithium grease in applications like lubricating your car's hood latch. Spray on WD-40© liberally to clean off any junk in the car hood latch/catch, clean with a rag as best you can, and after it dries, spray the mechanism with White Lithium Grease.

If your garage door chatters in its track channels, wipe the dust and debris from the channel after cleaning with WD-40© and after its dry, slather some Lithium Grease paste on the inside of the tracks. You can also apply a slight excess of Lithium Grease to the springs in the garage door to quiet the rattle and twanging.

If you have a squeaky rubber bushing in some shop equipment like a press, lift, or clamp; If you have any slowing or binding plastic-on-plastic part movement like in a drawer or lid, a dab of Lithium grease will quiet, lubricate, and protect plastic, metal rubber and such materials while not deteriorating them like a petroleum based lubricant would. Lithium grease is also water retardant, but not water proof! Make sure to not apply Lithium Grease to any metal which isn't BONE DRY! If you have a damp part, WD-40© is a perfect tool to clean and dry your part before lubrication.

You can also literally just spray a rubber or plastic part with Lithium Grease (or just silicone oil, which is cleaner and much better for rubber and plastics but IMPOSSIBLE to clean, so DO NOT SPILL and wear gloves. Seriously: https://news.ycombinator.com/item?id=30286616 ) to protect/shine them up. It will work totally well on your tires, but I don't like that idea because it might fling onto your paint or transfer to your rotor if you touch it while swapping wheels. Seems it might work well to prevent dry-rot during storage, now that I think about it. I feel like basically nobody does this though.

Thank you for this opportunity. I had a lot of fun thinking about one of my favorite lubricants, which is of course silicone, and I expect that it will add much value to your life!

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[edit: all the references to WD-40© in the More Suggestions part are true, but also jokes used to illustrate the marketing genius of WD-40©. You don't need it, and there's a decent chance that what you're about to spray it on will only get worse, but yeah, it does work really well. I also just think its pretty funny to have a can of WD-40© while knowing its true purpose, so that when some jerk like me comes along with his or her "AKTUALLY, WD-40© is a solvent not a lubricant!" you will then be free to utilize whichever form of verbal jui-jitsu you desire in dispatchment of this interloper as you reply, "Yeah! I use it every day … !"]

People who know the formula for WD-40