Originally Posted By: crazyoildude
does different gas really make an engine run different or is it in our heads?
Sometimes. Note that the octane number is the average of two methods, motor octane and research octane. One gas might have higher octane by the motor method, another might have higher octane by the research method, but both average to 87. Your engine might prefer one and my engine the other.
Also, some refiners cut corners. A few years ago I was buying about $500,000 in heavy fuel oil every five weeks. An independent surveyor was hired to gauge the tanks and run lab tests on the fuel. He told how he was hired by the local refineries when they bought, sold, and swapped product with each other (a common practice). One refinery, then ARCO pre-the BP takeover, was always low octane. The other refineries noted this, reblended the gas, and adjusted the price they paid to ARCO.