Hard to tell in my case since both of our current vehicles have no physical dipstick. The computer monitor works fine. I like the iDrive display better than the non-iDrive display we have on the X3. It goes down a litre over a period of time, usually 5000 - 8000 km, then I add a litre. I carry a litre in the back in the BMW top up oil case (holds one litre, paper funnel, disposable gloves) so that I don't have to go looking for Castrol if the light ever comes on. It isn't worth worrying about, just drive it. If it ever does get to the minimum, it is the appropriate time to add oil. Remember that there are still 7+ litres in there at that point.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue