I'm gonna spar with you on this quote....In the Marines, your weapon was kept cleaner than your dick. We would spend just about every minute of down time on field ops sleeping or cleaning our weapons and shooting the ****. We'd go through Q-tips like nothing, 10-20 per cleaning session. We would get those 16's sterile and then we'd lube them up with CLP and stow them or move on. Next day or 2, we'd break then out of the armory and start all over again. First few Q-tips would be slate gray...WTH? The CLP would leach the carbon out of the parkarizing or the base metal itself. Not saying motor oil would do this from the iron blocks but CLP was basically detergent oil. Burnt hydrocarbons and soot in the oil make it black, probably not a whole lot from the exposed metals in the block. Bypass oil filters (toilet paper roll filter in a low pressure feed) would turn black fast and the oil would still be pretty darn clean.
