I'm considering (do-it-yourself) draining the old coolant and refilling with new on my '07 530i. I've only owned it since 09/2010 and 27K miles. It still has the original coolant in it. I've read and understand the automatic bleeding procedure, but would like to know of any problems that others here may have had with that automatic procedure bleeding effectively. Thanks for any input/suggestions!

The bleeding (venting) procedure that I've read, for the N52:

Fill coolant expansion tank up to lower edge of filler neck with recommended coolant. Close cap on expansion tank. Do not open the coolant expansion tank cap during the venting procedure.

1. Connect battery charger.
2. Switch on ignition, do not start.
3. Set heater to maximum temperature, activate "Automatic" button, then reduce fan to lowest setting.
4. Press accelerator pedal for 10 seconds to floor. Engine must not be started
5. The venting procedure is started when the accelerator pedal is pressed and takes approximately 12 minutes.
6. Then top up fill level in coolant expansion tank with 250 ml (or about 18mm) above max. (only when venting (bleeding))
7. Check cooling system for leaks.
8. If the venting procedure has to be carried out several times, allow DME to drop completely (ignition key removed for approximately 3 minutes), then repeat from step 3.