I talk to a guy on the CumminsForum. he was running the Egr delete with the Dpf delete for some time. He felt that the oil was cleaner than a 5. 9.
when he was just running the DPF delete. he pulled a gallon of oil when doing a oil change. he let that oil set for a couple of weeks. he said the stuff that settled to the bottom was not pretty. it was like a sluge. that was the deciding factor for him to delete the egr.