Being a fellow BMW driver (e38 and e46), I find that it is my duty to point you in the direction of Motul oils.
Doing the regular filter change every 5000km, and topping up the oil, let me tell you that the Motul stays perfectly clear up to 15,000km.
I'm sure it'll go past 15,000 km, but given the weather here I'll be changing the oil in the e46 for GC.
I'm used OEM, M1's 0W40 in the e46 and I agree, both those oils because uber black in the matter of minutes.
In the e38, I've just switched to 5W40 for the winter time and so far, car runs nice and smooth. In the summer I put in 15W50.
On the downside, the cost of Motul is much higher. $35/2L Plus another $50 if you decide to use their fuel system cleaner and engine cleaner every oil change (not filter change).
Now, if only someone could help me out as to which Motul antifreeze i can use in BMW.
