The car's computer (maintenance reminder, flex service) not only tells you when it's time for maintenance, but it's also programmed to fatten your dealer's wallet.
We were not using our 2004 as a daily commuter, so the mileage was very low. The service indicator did not come on for two years while the car was under the maintenance warranty. The dealer would not perform maintenance until the indicator came on. They finally did, but only after I complained to the fat cats.
The B service was done, and I checked the results -- they didn't even check the air filters (unbelievably filthy). Not trusting what else they claimed they did, I changed the oil.
I have been doing my own maintenance. DON'T TRUST DEALERS.
Not changing your oil for 10K miles, or waiting for the indicator to come on, only invites major repairs, or better yet for the dealers, a new car every few years.
Synthetic or not, hange your oil 3 to 5K miles or every six months, whichever comes first.
I'm with you on a couple grounds. I've seen the inside of these engines that had extended oil change intervals. Not only is the buildup impressive and shocking sometimes, but secondary issues sometimes arise, such as breather/crossover ports or any type of small orifice passages getting clogged. An old friend of mine is a BMW tech, and he saw such things in the cylinder heads of those engines, including v10's, that needed head replacements because crossover passages were completely blocked. When the change schedules were revised, the problems went away. From what I've seen, I've been pretty impressed with how BMW reacts to such things, when compared to MB.
Additionally, even though modern oils are meant to resist this, and do pretty well, they can and do oxidize while just sitting around. That is typically minor, however.
I have the older type of system in my car, where it bases the change on miles, RPM's, and hours of use. I still change it before, but it does come out to something like 8-9000 miles between changes, which I'm ok about. I go about 7,500 on longlife oil. I can get the factory fill Aral oil here, but it's prohibitively expensive, so I just use Liqui Moly Toptec 4100 5-40.
The later type might work better, but it also can't sense all oil conditions that would necessitate changing. This is why the owner has to use common sense as well.