WD40 is great for dealing with things that are rusted in place, which is what it's supposed to be used for. It's just that it's not a great lubricating oil, and people often recommend it for use as that. Too thin and leaves a waxy residue to repel more water from rusting the surface, which you often don't want in things that you're lubricating.
I don't smoke, but I absolutely adore the sound that a Zippo makes when flicked open and struck, and wanted to get one a while back. I was kind of appalled at the fluid pricing -- the Zippo-brand fluid is even pricier, and I've seen the Ronsonol fluid itself recommended as a lower-priced alternative.
There are a lot of other things that people can burn in the refillable lighters, but I went through various testing that other people did and tried some myself, and none other than naphtha are really satisfactory. Some -- like white spirits -- aren't volatile enough, and won't maintain a consistent flame. Some, like gasoline, or low-water-content isopropyl alcohol, are too volatile and evaporate even more quickly than the regular fluid does or risk making an out-of-control fire.
Also works for the hand-warmers, which use the same fuel (and go through a great deal more of it than the lighters, so it's more-important there).
On an side note, I really wish that lighters of that sort would introduce some type of gasket that isn't dissolved by the fuel to help reduce the fuel vapor leaking out of the device when closed, or maybe some sort of other mechanism that seals the fuel reservoir off when the lighters are closed. As it stands, for a regular smoker, the fuel loss isn't a huge deal, but for someone who infrequently uses a lighter of the sort, the fuel loss is much more obnoxious -- it only takes several weeks for the reservoir to empty itself, in my experience.
If it's a rubberized coating on new devices, it may be a similar formula that doesn't have the degradation problem. I haven't personally had any devices do that in several years (not saying that there aren't products that do, mind).
And I remember that when the coating was new, before it broke down into a horrible sticky mess in a few years after purchase, it did feel pretty good to me. And it seemed pretty durable -- like, it didn't wear through or anything.
Just that when the Stickyocalypse did happen, it was awful.
I remember reading on Reddit once that people who bought a variety of dress shoes with a particular type of substance used in their soft soles had something similar happen. For a few years, many types of shoes from different manufacturers would break down and degrade in the closet. You take them out after a couple years, and they just crumbled apart. Wasn't a sticky mess, but I bet that people who rarely wore those shoes were pretty irked.
Anyway, point is, the industry moved away from that particular fiasco after a couple of years when the problem came to light, switched to similar substances without the problem. I wouldn't be surprised if the electronics industry has done the same.
The lighter fluid that the parent poster is talking about, Ronsonol, is not the stuff that goes in butane lighters, nor is it the "lighter fluid" used to start charcoal barbecues. He's talking about the stuff that goes into Zippo and similar refillable lighters, stuff that's also called "naphtha".
If you want to use it as a solvent with much frequency, you can get the stuff at dramatically-lower unit prices in much larger containers than what Ronsonol is sold at.
Keep in mind that this is potent stuff and can damage some surfaces. For example, another user is talking about using Goo Gone above to remove adhesive from paint on a wall. Naphtha is more-or-less paint thinner -- your wall's paint will dissolve in it. It'd be fine on glass, what OP is intending it for, but if you use it elsewhere, be careful with it, try it on a small amount of the surface somewhere first to see if it damages it.
It can also cause skin irritation. Probably not a big deal unless you're regularly using it, but worth keeping in mind.
I also have a container of white spirits, which are similar but less volatile.
The only time it's disappointed me was when I was trying to use it -- among a variety of other substances -- to deal with something other than sticker goo.
A few years back, a bunch of electronic devices were sold in the US that used some sort of rubberized coating that gave them a nice grippy feeling. Unfortunately, it turns out that after a couple of years, the coating degraded and turned into an incredibly sticky mess. I had a Grundig G6 Aviator shortwave radio that was affected, as well as a few other devices. It felt a bit like sticker adhesive, but trying to clean the stuff off with Goo Gone didn't work well (ultimately, isopropyl alcohol and a lot of elbow grease wound up being my most-successful combination).
But for what it is actually billed for, adhesive residue, I've had good experiences.
Note that Goo Gone, or at least the variant I have, has a quite-strong citrus smell, which I assume is there to mask some less-pleasant smell that the active ingredients have. So when I use the stuff, everything nearby smells like oranges for a while. Haven't had a situation where that's a problem yet, but thought I'd mention it in case it would be an issue for anyone else using it.
Expandability, or the lack thereof, was far and away the most controversial aspect of the original Macintosh hardware design. Apple co-founder Steve Wozniak was a strong believer in hardware expandability, and he endowed the Apple II with luxurious expandability in the form of seven built-in slots for peripheral cards, configured in a clever architecture that allowed each card to incorporate built-in software on its own ROM chip. This flexibility allowed the Apple II to be adapted to a wider range of applications, and quickly spawned a thriving third-party hardware industry.
But Jef Raskin had a very different point of view. He thought that slots were inherently complex, and were one of the obstacles holding back personal computers from reaching a wider audience. He thought that hardware expandability made it more difficult for third party software writers since they couldn't rely on the consistency of the underlying hardware. His Macintosh vision had Apple cranking out millions of identical, easy to use, low cost appliance computers and since hardware expandability would add significant cost and complexity it was therefore avoided.
Apple's other co-founder, Steve Jobs, didn't agree with Jef about many things, but they both felt the same way about hardware expandability: it was a bug instead of a feature. Steve was reportedly against having slots in the Apple II back in the days of yore, and felt even stronger about slots for the Mac. He decreed that the Macintosh would remain perpetually bereft of slots, enclosed in a tightly sealed case, with only the limited expandability of the two serial ports.
Mac hardware designer Burrell Smith and his assistant Brian Howard understood Steve's rationale, but they felt differently about the proper course of action. Burrell had already watched the Macintosh's hopelessly optimistic schedule start to slip indefinitely, and he was unable to predict when the Mac's pioneering software would be finished, if ever. He was afraid that Moore's Law would make his delayed hardware obsolete before it ever came to market. He thought it was prudent to build in as much flexibility as possible, as long as it didn't cost too much.
Burrell decided to add a single, simple slot to his Macintosh design, which made the processor's bus accessible to peripherals, that wouldn't cost very much, especially if it wasn't used. He worked out the details and proposed it at the weekly staff meeting, but Steve immediately nixed his proposal, stating that there was no way that the Mac would even have a single slot.
But Burrell was not that easily thwarted. He realized that the Mac was never going to have something called a slot, but perhaps the same functionality could be called something else. After talking it over with Brian, they decided to start calling it the "diagnostic port" instead of a slot, arguing that it would save money during manufacturing if testing devices could access the processor bus to diagnose manufacturing errors. They didn't mention that the same port would also provide the functionality of a slot.
This was received positively at first, but after a couple weeks, engineering manager Rod Holt caught on to what was happening, probably aided by occasional giggles when the diagnostic port was mentioned. "That things really a slot, right? You're trying to sneak in a slot!", Rod finally accused us at the next engineering meeting. "Well, that's not going to happen!"
Even though the diagnostic port was scuttled, it wasn't the last attempt at surreptitious hardware expandability. When the Mac digital board was redesigned for the last time in August 1982, the next generation of RAM chips was already on the horizon. The Mac used 16 64Kbit RAM chips, giving it 128K of memory. The next generation chip was 256Kbits, giving us 512K bytes instead, which made a huge difference.
Burrell was afraid the 128Kbyte Mac would seem inadequate soon after launch, and there were no slots for the user to add RAM. He realized that he could support 256Kbit RAM chips simply by routing a few extra lines on the PC board, allowing adventurous people who knew how to wield a soldering gun to replace their RAM chips with the newer generation. The extra lines would only cost pennies to add.
But once again, Steve Jobs objected, because he didn't like the idea of customers mucking with the innards of their computer. He would also rather have them buy a new 512K Mac instead of them buying more RAM from a third-party. But this time Burrell prevailed, because the change was so minimal. He just left it in there and no one bothered to mention it to Steve, much to the eventual benefit of customers, who didn't have to buy a whole new Mac to expand their memory.
They should really have used a polling site off Reddit to avoid that, but then, I suppose that if Reddit honestly got caught fiddling the scores -- like, say, a huge instant jump at the end -- that would be pretty catastrophic from a PR standpoint for the admins doing it.