#1
hey, so i have this kind of capo:



and the screw/bolt device/ mechanism has seen better days. i was thinking about oiling it up somehow, but i wasn't sure what to use. do you recon i would be able to use WD-40 or something similar, or just oil, or this might be stupid, but i was thinking about finger ease? just looking for something that i would be able to wipe clean so as to not screw up my strings/finish....

any suggestions?
#2
It's always best to avoid wet lubricant if you can. It builds up grime and dust after a while which only makes the problem worse.

I'd try to take the thing apart, get it all cleaned out with WD-40, then wipe that off as best as you can and get some graphite in it.
#3
WD-40 does a number of things well, like displace water (which is what the 'WD' stands for) and penetrate well, but it's a piss poor lubricant.

A couple of drops of light machine oil like 3-in-1 oil might work, or maybe even a dry graphite? (You could try running a pencil over the threads and then working the mechanism in and out, it's cheap and quick if it works, and it often does...)
“Ignorance more frequently begets confidence than does knowledge.”
Charles Darwin