Well I am a newbie here but my 535i blew a coolent hose and the engine overheated about a year and a half ago. I also had the oil level warnings shortly afterward. Turned out my headgasket was leaking. Blowing a coolent hose can be caused by pressure buildup in your coolent system caused by a faulty headgasket. Check your oil for any white residue (caused by coolent in your oil) and check your coolent reservoir for any oil floating on the surface. Hopefully this is not the case.