Gasoline So I have a couple of questions about gasolines... 1. My gov't professor mixes a bluish fuel and a clear fuel for runs in his modified porsche gt2. Question is, is there a benefit to doing that? Why not just put one or the other? 2. Does anyone believe or have experience in the fuel additives which some gas companies (shells "v-power" or whoever uses texaco with "techron") that supposedly "cleans" valves? All of Texaco's gas, from least grade to top grade, is said to have it. While only the top grade of shell supposedly cleans whatever... I remember having a topic some time back about buying separate fuel additives and that thread concluded in "if your car is running fine, leave it alone" kinda words.