After my reply to this post I recieved this message from VX crazy and a -3 rating on my reputation: "VX was designed for low octane and has knock sensors - unless running a blower or higher compression, hi octane is a WASTE and serves NO PURPOSE". I would like to respond by saying that Isuzu had the foresight that high quality octane fuel may not always be available where we go and put these sensors and capabilities in place to compensate for that. Burning good fuel keeps your plugs clean and gives the engine the fuel it needs to perform properly. If octane wasn't an issue, we could all use water. I don't know how to get the negative points off my reputation but I don't think it was fair. Burn chain saw fuel in your VX if you want to, VX crazy, but I'm putting the good stuff in mine.