I knew the oil had just been changed when I bought the car. At right under 3,000 miles of ownership, I decided to change the oil. It wasn’t a magical interval for me, but it just felt like it was time. I didn’t want to get too caught up in the great oil debate, so I took some direction from the forums and went with regular (i.e., non-synthetic) Castrol GTX 20W-50.
I’ve since started to use LiquiMoly in my Audi RS4, so we’ll see if I change my mind about the M5.