Re: AR lube
I like TW25B, or Militech. You could also get it in grease in a syringe like the Militech, but not an oil, just a heavy white grease. This is what many manufacturers told me that they use in their builds instead of the white lithium grease that the old military manuals call for. It also works great on trigger groups that won't be getting too gritty.
This stuff works great on pistols too!
I agree, you don't put too much oil in the AR. There are certain lube points, I think you'll find those in the manual, but heavily lubing the carrier isn't recommended. There are few parts that get lots of lube in the AR, more that get light lube.
Then I like to use CLP, it IS cheap after all, mainly to just coat and protect the metal, such as barrels, etc.
Any of the finer oils, CLP included, will soak into the pores of the metal over time and increase their resistance against rust. So even though you don't want to coat the carrier in oil, you do want a fine, very thin coat that you build up over time, and this will help slick it up some and protect it from the elements.
Machineguns were a different story. Anything beltfed basically came with a water spray bottle filled with CLP and that was just sprayed all over the tray and feed mechanism. When dirty, they wouldn't work any other way. But the AR is more delicate and if you overdo it, you can significantly reduce the reliability of the system.
This is all from my experience. I've been building 'em and shooting 'em before and since the army and their advanced infantry/SDM program. Also, if on a budget, the CLP isn't a bad choice. That TW25B can get costly.