I have a 760LI. I have gone out of the warrenty from the stealer and have finally had to do my first oil change.
I looked all over for the solution to this quandry and have found it different for my car by one small step from everyones stated resolution on the 750LI. You have to have the car running to reset the oil light. On my car if you do not have the engine running the menu is completely different and you cannot get to the reset area!!
I have copied the details from the web on how to reset below.
1=Sit in the drivers seat,doors shut and key out of slot.
2=Put key into slot and press the start button so the ignition is on.(not started)
3=Wait 5-7 seconds,then press and hold the button in the cluster top of speedo dial.
4=Hold this button for 5-7 seconds and a menu should come up in the middle of the speedo dial when this happens let go of the button and then to scroll through the menu use the same button in the speedo dial until you come to the oil millage.
5=Then press and hold the same button again for 5-7 seconds and the next menu should come up in the rev counter dial,scroll through this menu to reset and press and hold for the last time.
This should reset your millage for the oil.
Again, this may be unique to my car based on the settings loaded by the dealer, but it frustrated me over 5 days looking for a 760LI reset procedure. Hopefully it will help you!