Pitbull, sounds reasonable, but confirm with an analysis to be sure. A retired Mobil 1 corporate rep told me a few years ago that the shorter your trips are, the more often you need to change your oil. (I already knew that, but I let him say his whole spiel.)
BMW currently has a surprisingly simple scheme: the oil service computer (part of the instrument cluster) has a factory-set quantity of fuel that it monitors for the oil life. I don't know what that quantity is for each vehicle, but just say it's 750 gallons. Since the instrument cluster is constantly in communication with the engine computer (DME), it always knows the volume of fuel being injected while the engine is running. It also knows and indicates distance traveled. If you tend to drive the vehicle hard and accelerate fast, drive at high speeds, idle a lot, drive short trips in cold weather: these factors all contribute toward using up that alloted 750 gallons while traveling much fewer miles. This will greatly shorten the oil service indicator mileage. However, if you do the opposite of the above, increasing your fuel efficiency, it will lengthen this mileage for a longer OCI. I'm not aware of any other parameters that are monitored on current BMW models for oil life. Almost seems too simple. Someone correct me if you have updated info.
