There was a thread out there somewhere quite a while ago where the user posted pictures of his car's valves when he had everything apart at some 100,000+mi service. He noted that he used exclusively Shell V-Power gas. The valves were insanely clean and were enough to convince me to use name brand, premium fuel in my car. Now, at 167,000mi, I replaced the oil separator and had my indy mechanic take this picture in the process. I have used Shell V-Power 93 and Phillips 66 Premium in my 2006 E90 330xi sport manual since I bought the car new in 2006. I also use a can of Ventil Sauber and a can of Jectron just before every oil change. Having seen only the opposite results in the past (granted on not exactly performance vehicles), I feel this image speaks for itself. If it wasn't the good gas and additives, I don't know what it was that kept this engine so clean. I plan on driving this car until the wheels fall off and I can't get them back on again. Don't cheap out on gas, guys!