Hey guys i just bought a 2006 Audi A8 4.2 with 129k miles and im wondering would 5w40 fully synthetic oil be ok to use? The previous owner used 0w40 but i got Castrol EDGE 5W-40 Advanced Full Synthetic Motor Oil with a Audi oem oil filter. I live in Chicago and temps now are between 20s-40s. I just thought 0w40 is a bit thin considering the miles plus i think Audi calls for 5w40. I wont be driving the car much in winter but in spring n summer more often so thats why i was thinking to put 5w-40.