It's a mixture of light mineral oil and light mineral spirits. As a lubricant, the mineral spirits carry the mixture into crevices, then evaporates, leaving an oil film behind.
This is either useful and appropriate for a situation, or it's not. Also, the oil might not be a specialized oil for any particular use, but a lot of applications don't need a high performance oil.
In my view, the drawbacks are:
1. Controlling overspray. This is why, even if I liked the stuff, I'd prefer to apply it with an eyedropper in many if not most cases.
2. General ignorance about lubrication needs, where something else is preferable, such as grease, a suspension of wax, penetrating oil, etc.
On the other hand, keeping a supply of every possible lubricant can be a storage problem, and I've gradually come to prefer using the "wrong" stuff than buying yet another oversized container of something that I have to keep forever or dispose of.
I learned a lot about WD-40 from this project! This is a highly debated topic, but their website leans into the fact that WD-40 is, indeed, a lubricant.
> While the “W-D” in WD-40 stands for Water Displacement, WD-40 Multi-Use Product is a unique, special blend of lubricants. The product’s formulation also contains anti-corrosion agents and ingredients for penetration, water displacement and soil removal.
Regardless of the facts, when all was said and done, they were the ones judging the entries, sooo… yep, it's a lubricant.
It is a lubricant, just not a very good one for most uses. It can't bear much load and it tends to just dissappear in a short time.
I once replaced a series of mortice lever locks in a first house that were very worn after a decade of use. You had to shake the key to get them to open. I was amazed on opening them to find them completely dry, when they come greased. I suggested they lubricate the replacements occasionally. They replied that they sprayed them regularly with wd40. This has washed the grease out and left... virtually nothing.
I think that's one of the biggest screwups people make with WD-40 is that it's basically just a petroleum solvent and other than maybe initially unsticking things, it often makes the problem worse. As far as solvents go it's not particularly great, and in terms of lubricating or breaking free it's pretty bad. I'm surprised they still sell as much of it as they do (chalk it up to good marketing), when for basically everything there's a better choice (protip: if something is really stuck, the best tool provided you don't have dogs or children getting near is going to be acetone mixed with a good ATF).
Jack of all trades, master of none. It is a better lubricant than most solvants and a better solvant than most lubricants, it will always be worse than a specialized product, but if you are only allowed a single can, that's a good choice. Affordable and widely available too. Oh and the pressurized can form factor is convenient.
Hate the smell of ATF but it was a life saver on some hinges that I wanted to save, but I couldn’t get to move after trying penetrating oil, wd-40, and some other things (not in that order ). ATF after a few hours succeeded.
This was in fact one of my big learning experiences in mechanical work. As a kid, my bike was running rough so i took it apart, cleaned oout all that yucky/dirty grease from the bearings using WD-40, and then reassembled it all only to find it was even worse than before. Only a few years later did I learn that wd-40 is a terrible lubricant for bike ball bearings.
You can see a similar effect with standard skate bearings used in fidget spinners - most bearings come pre-greased with a fairly high viscosity lubricant. If you spin the spinner, it will slow down quite fast, but if you take the bearing apart, clean out all the grease, and reassemble it, it will run wicked fast and long. Until some dirt gets in, at which point, grease would have worked better.
For what it's worth, old lock grease tends to move away from where it's needed and turn into a hard, waxy substance. It's arguably better to have a lock cleaned and slightly lubricated with WD-40 than one gummed up with ancient grease and dirt, or worse, rusted.
I've heard a lot of anecdotes in every direction: only use graphite, only use a cleaning solvent. I've never read anything authoritative and I suspect the ideal approach is to regularly (e.g. every decade) disassemble the lock, clean it thoroughly, and inject grease, but nobody is going to do that.
And yet, it lubricates! I've heard your claim a lot, but the fact remains, it makes machinery work more smoothly, by reducing friction, and it is effective over significant time periods. By any definition, it is a lubricant.
> Myth: WD-40 Multi-Use Product is not really a lubricant.
> Fact: While the “W-D” in WD-40 stands for Water Displacement, WD-40 Multi-Use Product is a unique, special blend of lubricants. The product’s formulation also contains anti-corrosion agents and ingredients for penetration, water displacement and soil removal.
I don't remember the source and forget many details, but the test was very compelling. The guy used approximately a dozen different products, clp, wd40, etc. The test involved individual identical pieces of steel all coated with each product and left in wretched environment.
The control, ie uncoated piece of steel fared better results that the regular WD40. I remember the best being Clenzoil (I had to grab my can to remember this). However, among the best was.... WD-40 specialist, specifically the "corrosion inhibitor" version. I think it was either the second or third best and I consulted my other can to remember this.
Sadly, my favorite lube ranked very poorly, which was Balistol; however, I'll never give up my Balistol.
I have put both the Clenzoil and Specialist to various 'tests' over the years and can vouch for their quality. But I'd use snot before regular WD-40 unless I was making a stink bomb.
Edit: While not the test mentioned, ProjectFarm (youtoob), who does myriad high quality evaluations, did test various lubes, but I think mostly for lubricity. It was also revealing and I highly recommend it and the channel in general.
Water is a lubricant as well. And yet it is not a good lubricant for all applications. WD-40 is absolutely spectacular for certain things, but if what you want is a lubricant there are much better options. For instance, there is a silicone version that will make a sticky old lock work like new.
> And yet it is not a good lubricant for all applications
seems like a bit of a straw man, no?
> a silicone version that will make a sticky old lock work like new.
In my apartment, my deadbolt was so sticky that it was hard to turn even with the door half open. Two spritzes (keyhole and the bolt) with WD-40 classic, and it moved easily, and continued to turn easily for the remaining 6 months in my time there. Could lubricant-X have done a "better" job? Maybe, not that it mattered in practice.
If NASA designed an even better lubricant, would lubricant-X no longer be a lubricant at all by your standards? Because now there's something that can also unstick your lock, but with an even lower coefficient of friction?
WD-40 contains lubricants, and it can be used as a general-purpose around-the-house lubricant. Proven by my years of personal experience. Trying to claim that it isn't a lubricant is like trying to convince me that my lightbulbs are dim. I just laugh and move on.
> In my apartment, my deadbolt was so sticky that it was hard to turn even with the door half open. Two spritzes (keyhole and the bolt) with WD-40 classic, and it moved easily, and continued to turn easily for the remaining 6 months in my time there. Could lubricant-X have done a "better" job? Maybe, not that it mattered in practice.
It was likely the solvent properties of WD-40 that helped. It dissolved the old, tacky lubricant or rust and left you with a cleaner lock. For a six month fix on a rental, that is probably fine. For a long term fix on a house you own, it may be worth using one of a plethora of lubricants designed for that specific use case (including a more specific variant of WD-40 that is designed for locks and leave behind a dry lubricant when it evaporates.)
> Because now there's something that can also unstick your lock, but with an even lower coefficient of friction?
WD-40 is decent at removing rust, but not great at repelling water and thus preventing rust.
There are a lot of things that go into picking the right lubricant for a specific application. It isn't just "which lubricant is slipperiest?".
WD-40 is indeed a lubricant, but much of the benefits of using it are due to its solvent properties and people often don't understand that applying it in the wrong circumstances can lead to removing the correct lubricant and result in less lubrication.
It's a solvent (penetrating oil), so it dries out. It works well to unstick whatever might be causing trouble with the door lock mechanism. If you use something like a silicone lubricant, you'll go a lot longer before needing to reapply.
