I'm convinced that a lot of the black stuff that comes out of the chains innards is something (teflon?) in the lube itself. I have super cleaned my chain, taken it for a short ride (10 miles) and cleaned it again. What do you know, more black gunk! And I ride a clean, paved MUP, so, It's not all dirt. It isn't ground metal either. If it was, chains wouldn't last very long. bk