I forgot to mention that I have a bypass filter installed. (Spinner II).

The job of good oil is to keep the soot particles down to a small size and keep them in suspension. The new CH 4 and CI 4 oils do that very well.

The condition of the engine makes a major difference also. If you have a lot of blow by then your oil is going to load up faster. That is why to be safe you should change it at 3000 miles unless you run an analysis.