On the back of my BMW Rider's Manual (US Model) is says "BMW recommends CASTROL" on the inside is says 20-50. Doesn't say I should use BMW oil. I'd think CASTROL oil from the auto parts supply store would work just fine. It's what I bought. I did buy a BMW filter based on some of the discussion here. Once my warrenty is up I'll look for a different filter.
Bruce H, 10/1200GSA, 07/Dakar, 07/K1200GT,04/R1150R 07/1200GSA,traded, 03/RT-sold, 2000/LT-sold, 99RT-sold, 99GS-sold, 96GS-sold, hers: 99/R1100R, 06/F650