Yeah the FSS (Flexible Service System) from Mercedes-Benz is more clearly described in Mercedes-Benz manuals over the Chrysler XFire manual. Yeah it also calculates sitting time. So if the car is stored for say 6 months or a year with no use, the FSS system will also calculate that sitting time into oil quality and reduce the oil life by a thousand miles or so. Again it still depends on ambient conditions, driving style and time.