You should join the BMW CCA (Car Club of America). The dip stick and run flat tires are favorite rants that show up in virutually every issue of the Roundel - the club magazine. My personal aspect of the dip stick is the 2 times I have changed the oil myself on my 128i, I added 6 quarts and checked it, like I usually do, and it read full. It is supposed to take 7 quarts. Is the sensor wrong? How do I know? Pretty hard for a dipstick to fail.
The BT tool will allow you to code for a new battery as long as you put in the same type and size. If you want to switch to a mat type battery or install one of a different size, then you want NCSExpert (available free). You need a cable for NCSExpert to allow your OBC2 signals to be transmitted to your computer. I paid about $100 for mine.
I believe another poster is right, you can adjust volume on the gongs without coding. Coding would allow you to turn the gongs off in some circumstances. I also coded to cause my car to unlock itself when I remove the key. You can change a lot of annoying things with coding. But you can't give the car a dipstick.
128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport
Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09