Hello all! I'm new to the forum and a new purchaser of an Audi s4. I have been reading extensively in what oil to use for my car. The manual says 5w40. I've read that many people use 0w40 and even 0w30 if it's gc. After reading I've come up with 3 oils in interested in. I primarily want something easy to get at local stores so that limits me. I am considering 0w40 Mobil 1, 0w40 castrol, and rotella t6. They are all readily available to me. I live in Massachusetts so the winters do get cold sometimes below 0. I've read 0w is excellent for winter use and I will most likely use 0w in the winter or maybe even all year depending on what recommendations everyone here has. If I end up going with t6 I want to know which 0w will be best in the winter or even all year. Thanks!