On the occasion of the death of the inventor who developed WD-40 as a water displacer, Ann Althouse says this:

...tell us about your WD-40 stories.

Honestly, I was beginning to think no one would ever ask, and I'm delighted that Ann Althouse gave me an excuse.

I've had so many WD-40 stories I wouldn't know where to begin. I can't live without the stuff. I've worked as an auto mechanic and a plumber, and as anyone who has to loosen nuts, bolts or pipes knows, a can of WD-40 has countless uses, and is an absolute necessity in every toolbox.

Usually, it works quickly and all is well. You just spray it on the stubborn part, allow it to do its stuff, and VOILA. The nut comes free. But occasionally (and if you're working on old cars or old houses, occasionally will happen more frequently than you'd prefer), there will be a case so stubborn that it's either WD-40 or defeat. When that happens, all you can do is to go through the ritual of applying WD-40, then hitting it repeatedly, then waiting, then applying WD-40 again, then hitting. And so on. Impatient people might find it hard to believe, but if you are patient enough and persistent enough, the stuff will almost always work.

The last such epic battle I had was in February, fighting a broken 1920s pipe coupling in Los Angeles. I didn't go there to wage war with an ancient coupling; I was just visiting a friend when the main water line broke and started spraying water all over the front yard. The break was right where the last accessible coupling joined the newer copper water main. To my horror, the coupling protruded -- barely -- from the end of another coupling solidly embedded inside the stucco and concrete foundation, and on the other side of that (in an inaccessible crawlspace with 12 inches of clearance) was the rest of a system of ancient pipes which branched off to supply the whole substandard apartment building. The coupling in question had probably been tightened too hard by a long-deceased plumber back in 1922 or something and had been there rusting in place ever since. Now, there's a principle in plumbing that you should not break pipes unless you are prepared to replace them, and if this coupling had been forced (which I easily could have done), instead of coming loose it would have either broken off inside the joint, or else broken the pipe beyond that. Which would have meant knocking through the concrete foundation, opening the crawl space and many, many hours more work (which no one was paying me to do). So I sprayed the WD-40, put the pipe wrench on, hit it as hard as I could with a hammer just short of breaking it, then spray some more. And prayed. And waited. Yes, the most important thing to do in cases like that is to wait, then spray some more, then hit some more, then wait some more. It literally does penetrate, but when something has been rusted in place for nearly 90 years, you have to be very very patient.

Tackling that pipe in Los Angeles was one of those instances in which I worried that I might have to give up. But the water was turned off to the whole building -- so giving up was not an option. (Not if I wanted to be comfortable and have running water during my stay there -- so this repair was not a purely altruistic outburst.) Nor was it an option to use excessive force and breaking the pipe. So I just kept slamming away, spraying more WD-40, then waiting, then slamming and spraying and praying over and over.

I don't know how much time went by as I wasn't looking at my watch, but finally I reached the point of no return. I was ready to give up and yield to the temptation of finally applying excessive force, and accepting the consequences. So I put on the pipe wrench, and really slammed it, over and over. It was loud enough to hurt my ears and I worried about the scale that the rattled ancient pipes would certainly be leaving in those poor tenants' pipes the next time they turned on their appliances.

Finally, after hitting as hard as I could for the umpteenth time, it looked like the wrench had slipped! Or had it? Nervously, I wiggled it, and whoa! the teeth were very much still embedded in the coupling. So I pulled, and to my enormous relief, it actually moved a bit! Lo and behold, it wasn't broken off. With a little more muscle, it simply unscrewed, and I took it down to the nearest hardware store and replaced it for few dollars (with a proper dielectric union, which the old one was not) then sweated it back to the copper main, rejoining the old system back to the new.

WD-40 had won again.