Generic stuff, got a big bottle and even with a couple spills i have a ton left...
and yes, if unoiled things can get weak. Had a buds air hammer than wouldnt go at all, had sat who knows how long... i put a good dose of oil in it and gave it 5 min to soak, it managed to start moving and roared back to life as the motor ran the lube through...
I put 2 drops in before i use a tool, and if it's been used heavily or i see any moisture, I'll make sure to oil and run it a few seconds when im done.
Has a boss one time, used his air gun, oiled it, thinking l was doing the right thing, He complained that I had oiled it, and now it was not working, or not working properly, told me he never oil's it.
I've used the marvel mystery, but then I bought a quart of mobil almo 525. I can't tell any difference between them. It's a little cheaper to buy the bigger bottle. It'll be a while before I use up a whole quart!
I use Lucas air tool oil. Pretty thick stuff haven't had any issues with it. Oil every air tool right before I use it. Figured it's cheap insurance instead off spending $110.00 to have snap on rebuild it. Also use an inline water separator at work.