I am pondering my next system fill and keep thinking about some posts here. Is it a gag or true that some here suspect GC to light on detergents/dispersants? One posted on heavy soot but others countered it could have been an unrelated problem. Second, can an oil produce great wear numbers while the engine dirties? The reason I ask is another post noted that ND oils are stout with AW additives, but no detergency. If I can not sort out this dilemna next oil change will be Amsoil Series 3000 HD or M1 5W40 truck & suv.