I changed the oil in my '94 530i two weeks ago. I don't know what was in there before, as it is the first time I've changed the oil since I purchased the vehicle a few months ago.

According to the OBC, and my general calculations of fuel consumption extrapolated over 3 months of daily driving in Michigan, the results are as follows:

Driving style is the same. 100miles /day. 95% highway. Speed:yes Mainly btw 75-85 with jaunts to around 110 (when the wheel imbalance shows).
Old oil - Black, like molasses
Milage before oil change 21.6 mpg at the end of virtually every tank.

New oil 5-40 Mobil 1 Syn.
22.8 mpg. After 3 weeks of driving, the oil is still relatively clean.

I figure that the filter was the biggest source of problems, as it was horrific (essentially looked like the filter of my 5yr old shop-vac).

We'll see what the next 3500 miles bring.

BTW, just crossed the 100K mark today.