Light oils don't work well in good weather especially junk oils like rem oil. In cold weather its sometimes worse than nothing.
I use 30 weight non-detergeant motor oil for gun lube. It doesn't breakdown under thermal abuse and doesn't freeze.
You really need to learn to service your firearms rather than having someone else do it. I would suggest the army marine field manual on the m4 carbine its close enough to the ar15 to be usable. Can't link up to a pdf from this device but some kind soul I'm sure will.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent