I changed my oil a few days ago at ~5800 miles. Here is what I learned:
1. I woud have gladly paid a few hundred dollars more for the car for a dipstick.
2. If the S65 had an ununsed plug in the engine that was somehow magically in exactly the right spot, I would happily invest the time and effort to retrofit a dipstick.
3. I find it hard to believe that BMW race engines do not still have dipsticks. You would think BMW would go for some ///Marketing points with "M cars are old school and still have dipsticks".
4. I do not have a mityvac and I did not remove as much oil as Greg did. I drained the oil and used about 8.2 liters of new oil, and the oil level indicator read slightly above the min mark after a round trip drive. I added another .2 - .25 liters of oil. After ~10 minutes of my drive in to work this morning, the level indicator had not moved at all. So maybe the indicator cannot see .25 liters of change, right? Just before I got to my gym, I went down a long, steep hill. In the midst of the hill the level indicator jumped up to about 2/3 of the way up to the max mark. From the gym to my office, the level indicator is still reading at the 2/3 mark.
I would prefer to fill my oil to the nominal/mid mark. My dealer went to the max mark at the 1200 service. Maybe this is as close as I am going to get. Seems like an inaccurate system, based on how my indicator behaved today. It definitely makes oil changes harder.
The mechanical part of the oil change is quite easy. I was happy with access and orientation of both drain plugs. The oil filter cap will leak oil however, so be prepared with paper towels when you start to open it.