Usually, if the oil is black early, it is caused by running too rich, a really bad thing for the engine, as it leads to build up on valves (poor valve to seat cooling and sticking valves); piston rings "carboned up" and poor ring to cylinder seal, and lastly, overly rich mixture washing off lubricants from the cylinder wall, destroying the dynamic seal, and allowing potential ring to cylinder contact (scuffing). I lean every 1000' in the climb, and lean to peak at 65% cruise, higher EGT, but lower CHT. Been running over 40 engines that way, and they still look good at TBO!
DAR Gary