engine oil low on 650i but oil is full
Do you mean that the oil pressure is below minimum but the level is full? If so do not drive or engine damage will occur, have it toed to a shop of your choice and have it checked out, could be a gauge or sender failure but better safe than sorry.
Are you referring to the oil level according to the driver information computer? You might want to check for codes. Does your car have a physical oil dipstick? Sorry... I can't help you much unless you have a full BMW scanner program. These newer Bimmers are a pain with the electronics.
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