[MikeMike]

It isn't that complicated. Ride the thing for 30 minutes and if you don't have a centerstand, lean it against the wall and check the level with the dipstick sitting on top of where it goes ie. not screwed in.
I've got 40,000kms on my bike and it hasn't burned a drop between oil changes, ever. It's ridden in temps from near zero to well over 100 degrees on a regular basis, at sea level to over 13,000ft on a regular basis with highway cruising at 85mph being normal. The drain plug is still clean, I change the oil every 2,500 miles, usually, and a filter (the last 3 changes have been with a Hi-Flo filter and not the overpriced BMW part), I have never been comfortable with the BMW recommendation of changing the oil every 6,000 miles.
I use Castrol 20w-50 because that is what the dealer uses but they charge well over twice the price for their BMW oil that is the exact same oil. The BMW dealer only uses and only stocks 20w-50 oil and will not source BMW 10w-40 oil, so figure that one out.
A 1/4 of a quart every 2,000 miles is odd, I've never heard of anyone burning oil with a 658. That would mean your oil would be a half a quart low at oil change time.