HI, I'm new to the forum, and I know this subject has been discussed ad nauseum, but no matter where I look, brick and mortar stores or on line, I can't locate and buy the German Castrol. I own an Audi A4 1.8 turbo, '03, and a BMW 530i, '05. I use Mobil 1 0w40 in the Audi. The BMW calls for 5w30 synthetic, BMW, or Castrol. I know the BMW- Castrol relationship is mostly marketing, but I really would like to use it. I live in Morgantown, WV., not exactly the heart of whats happening, so where can I find the oil, and what do you folks suggest? Thanks!