I'm running Series 2000 0w-30 right now and while checking the oil today, I noticed it was fairly dark. I only have 2,800 miles on the oil. I've run M1 and Amsoil the last two times so I don't know why it is so dark already. M1 stayed lighter longer, and I believe the Amsoil 5w-30 did as well. Any ideas why this is happening? I'm supposed to take this oil to 6K-8K miles for analysis, but if it becomes darker, I'm more likely to shorten the drain interval. I know color doesn't always mean the oil is bad. Maybe it's time for me to use my AutoRx?