I have heard a lot about Chevron Techron fuel system cleaner. Today I was passing by a Chevron gas station and noticed the Chevron gas comes with Techron pre-mixed. So does that mean using Chevron gas in my car will keep the fuel system automatically cleaner - thereby keep car running smooth?? I have also heard from people that Shell, even though its comparatively bit expensive, is a superior brand than am/pm, 7-eleven or other brands, but they dont say in what respect. If I am concerned about FE and overall performance of my car, should I be choosing one brand of gas over the other?