The puff of oil on initial start up is classic valve stem oil seal failure.. The reason it did it is that the oil will seep into the bores irrelevant of changing the oil or not..
This is an interesting thread thats worth a read..
http://www.bmw-sg.com/forums/r2d-autoworks-pte-ltd/67932-oil-consumption-problem-read-here.html
This is an interesting thread thats worth a read..
http://www.bmw-sg.com/forums/r2d-autoworks-pte-ltd/67932-oil-consumption-problem-read-here.html