Thanks for all the help once again. Btw i forgot to add that I stay in Asia and the weather here is averaging 28c to 32c, plus plenty of start-stop traffic. I can't get GC in my country and after some searching I shortlisted to Mobil 0w 40w with BMW LL-01 and the new Castrol Edge 0w 40w with BMW LL-04 approval. I like Amsoil and used it before, but it doesn't carry the approval n I just don't feel good. But its a great oil anyway.
Out of these 2 oils, I probably would choose Castrol over Mobil as Mobil 0w 40w is well known to thin down over time and also because BMW recommends Castrol. Now I have a question and I hope somebody can help to answer. What is the content of Castrol Edge? Is it group III or IV? Cheers!