Alright, here's my problem, I have a 96 accord with 126,000 miles on it that I have owned since 61,000 and ive used M1 10-30 in the summer and 15-50 in the winter. Changed it regularly at intervals of 3,000 to 5,000 miles, but never more. Ive considered flushing it, but ive heard that this will clean it indeed, but sludge up the oil screen/create leaks all throughout the system. Reason im considering is that the oil always seems to come out black even after only about 300-400 miles of driving, and it kinda bugs me. At the same time, ive considered changing over to RP because I can actually get the stuff cheaper than M1 because I live right near the production plant in Houston. Anyway, your expert thoughts on this would be great. Thanks