Yeah vettenuts, that was me with the brown sludge using BMW 5-30 for 10k intervals. I would either suggest that you split the BMW interval in half or use an oil with more cohones...whether that be Syntec 10-40, 5-50, or 20-50, M-1 0-40 or 15-50 etc...
I believe that A3 30 weight oils are a minimum requirement...hence, don't use M-1 5-30 or 10-30...nor Syntec of the same grade. Otherwise, an A3 30 weight will hold up a little better...but, from my experience NOT the whole 10k interval without breakdown and consumption issues....and these are bad (contrary to popular belief). You pick it....fuel economy vs. protection...it's up to you where you draw the line. That's why the GC is a good product (A3)...but I'm not using it.
In my BMW, Syntec 5-50 has held up well from my experience. However, I switched to Castrol TWS 10-60 too early to tell if it would have held up for the full 10k mi.. Otherwise, I've found it to be a better choice than any Mobil products (with maybe the exception of Delvac 1). Mobil product have consumption and poor engine sound characteristics. You pick the flavor. I'm currently on my second interval with the 10-60 and fuel economy, smootheness, power delivery and engine cleanliness are at their highest...oil consumption at it's lowest....
