My car runs shitty and gets CELs when I use it, I just figured out that that was the cause of the CELs I've been getting occasionally when I bought a tank today. My friend and mom have both had knocking problems apparently from it. I had to go buy 2 gallons of 100 octane race gas to put in the tank as soon as I had used enough to stop the shitty running and CELs, $6.25 a gallon. Their octane is definently lower than advertised. Don't buy Hess gas, it's not worth the $0.20 cheaper a gallon. :rant: