"TAG785" and "T/W" are part of the lot numbers of "GC", which is German Castrol. Early "TAG785" batches seem to have higher levels of iron which suggests slight contamination, but at levels not likely to harm anything.
BMW specifically approves of Mobil 1 5W-30 in E46s (current 3-series) and E39s ('97-'03 5-series) (what BMW do you have?), but I can tell you that Mobil 1 0W-40 and German Castrol 0W-30 also work well and are probably better because they meet ACEA (European automakers consortium) A3 (extended drain capable with high HT/HS) specifications.
The BMW HP Synthetic 5W-30 oil does give decent wear numbers, but it doesn't seem to hold its TBN well, and with time, it seems to leave a brown gunky deposit under the oil filler cap which is hard to clean up. I'm not sure what the significance of those deposits are, but I'd rather prevent them if possible.
I'm running GC in an '00 528i, M1 5W-30 in an '01 325i, and M1 0W-40 in an '03 330xi, and so far there's no brown buildup under the oil caps (but only approx 1,000 miles on each of them so far)
Congrats on the new car!
Jason
[ September 23, 2003, 10:46 PM: Message edited by: quadrun1 ]