I like synthetic oil. The manual in my BMW's advise to use only Mobil One or BMW synthetic. Their is a myth that you can go for longer oil change intervals. The technician at the BMW dealer advise that it is good measure to change every three months or three thousand miles. I use 5w40 BMW synthetic in the 2001 740iL. 10w40 MobilOne synthetic in all of my cars. Some of the BMW club members that track their cars at auto courses love AMSOIL products. Sincerely, Michael Pack Severna Park Maryland