ARs are supposed to run wet. Petrol based oils can tar-up if overheated. The ideal lube is one with high flashpoint and extremely low ash. If this is the case you can add it without subsequent gum-up. All lubes will vaporize inside an AR bolt carrier, depending, of course, on the level of sustained fire. Eventually, carbon powder from burnt gun powder will build-up and cleaning will be necessary. (I think of the inside of an AR bolt carrier like I think of a combustion chamber without an exhaust valve.) I personally believe that, without extreme build-up, the "carbon precipitates" will act as a dry lubricant for a period of time. The trick is to get the gun to run with as little wear as possible until the level of carbon demands cleaning. We have all seen the "ultimate AR meltdown" video. If we think about it, we have never been taught by anyone that you can fire 830 full auto rounds through an AR without cleaning it----let alone without adding lubrication. That DI AR did it without cleaning or adding lube----until the barrel melted and blew. That's why they change barrels on a machine gun.
