Comment by ndsipa_pomu

You're technically correct, the best kind of correct.

However, if you're looking to lubricate something and have it last for a reasonable time, then WD-40 is a poor choice. However, using WD-40 first to hopefully dissolve contaminants/rust and remove water and then after a quick wipe to remove excess, applying something better such as 3-in-1 or silicone grease etc is a good idea.

The clue is in the name - Water Displacement 40.

If you want a spray on penetrating lubricant, then GT-85 is usually better as it has PTFE included to better lubricate. It still won't last that long though as it'll only make a thin film.

Edit: I've just seen that WD-40 make mention of a bus driver in Asia using WD-40 to remove a python from his bus' under-carriage. If in doubt, spray it with WD-40.