A question on 91 octane gas!Out here in So.Cal. we have several brands available (Union 76,Chevron,Arco,Shell,Valero)to name a few. Is any one brand better than another for your engine? A friend told me that you don't see the name of the brand on the tankers trucks anymore because they fill up at the refinery and deliver to what ever brand is on their route so you would be buying the same gas at Shell station as your local Arco but at a higher price! Any body working in this field shed some lite? Also,he's running a 427 Ford with solid lifters and fills his tank 1/2 way with 91 octane (Union 76) then fills the rest with 100 octane Aviation gas,says it performs better with this mix! I thought that aviation gas octane was figured differently then automotive octane,so is he really gaining any benefits by mixing or on the path to destruction?  Aaaah the curious mind! SKIP