Question: what is the difference between regular midgrade and premium gasoline?
Answer: Octane is how much compression a fuel can withstand before igniting, or rather it's a measurement of a fuel's ability to avoid knock. ... Typically “regular” gas is 87 octane, “midgrade” is 89 octane and over 91 octane is “premium” gasoline. Some states label top-tier gasoline with 93 octane as “ultra” gas.