If you are not getting an oil low message periodically too, then you probably don't have a problem with the oil level/quantity sensor. Mine has needed the sensor for 2 years, and I have the sensor in hand, but I just haven't taken the time to do it. It will show oil hi one minute then -2.0L a few minutes later. And it is very sporadic. It sounds like you may have a little too much oil - its not really a big deal. Make sure your indie is draining all the oil and adding only 8.5 quarts. I do my oil change in my ML320 myself - its the easiest oil change to do of any vehicle I've ever owned.