I've become a big fan of the blue Lucas Extreme Duty Gun Oil. It comes with a nice needle tip on the bottle making is super easy to apply precisely. It seems to adhere well, doesn't dry up, and doesn't seem to attract grit. It's really good stuff--try it. I think you'll all like it. I got it at Premier Arms in Brownsburg, but most will have to order it online.
Extreme Duty Gun Oil
I like it but it causes my Steyr m9-a1 to not lock open on the last round. Everything else seems to run fine.