lawsoncl said:
Its original design purpose was to get water out of aircraft engine mechanicals and leave a light oil behind to inhibit rust. Personally I hate the stuff. It's not that great at loosening bolts, a lousy lubricate as it evaporates and leave a gummy film behind (as design) and a mediocre solvent. It does work okay on bike and motorcycle chains.
Contact or tuner cleaner would be my first choice.
WD-40 is a "water displacer," and works well for that purpose. To that end, I spray all my "in the white" stock with a light coat every six months or so, so it doesn't rust away before I get to use it.
I will - sometimes - use it as a cutting oil. If I don't have something more suitable to hand (I'd use spit, but I do prefer my cutting oils actually be "oil" of some variety.)
WD-40 as a lock lube? No. Dry graphite.
WD-40 as a contact cleaner? Gawd, no. It has made me some money in that respect, but I'm tired of that sort of thing. NEVER NEVER EVER NOT EVEN ONCE use WD-40 as a "contact cleaner" - you may as well just dunk the connector in ATF. Don't use it as a "corrosion inhibitor" either - there are products that do the job much more efficiently, without inhibiting connectivity.
WD-40 as a penetrating oil? That's not even farcical enough to be funny.
I probably go through one small can of WD-40 every two or three years - I usually end up having to buy one because I finally lost the last one (since I tend to re-arrange things every few months or so. Usually a few weeks before I'm due to coat my project stock again, even though I don't have much of it.)
If you want to
clean your connections, use electrical contact cleaner. The stuff based on trichloroethane is about best, but you can't find it anywhere anymore. I think most of them now are MeOH with some acetone thrown in, and that works fairly well. Brake parts cleaner is an acceptable substitute, with carburettor/throttle body cleaner in third place. I prefer CRC, as long as we're talking about brands.
If you can't find contact cleaner and don't want to use either of the other two, use acetone after using a rubber eraser to scrub the contacts clean (size permitting.) It is important that whatever you use to clean
does not leave residue - WD-40 is
formulated to leave a residue.
I've said it before and I'll say it again (and probably again next week...) "WD-40 is not a 'miracle in a can' - despite what people and marketing tell you."