Also, pump gas is not all the same. My brother had a 73 Pontiac GP and had to run 91 from the local Arco station.If he ran anything else from Arco, it detonated. If he went to Shell, he could run 87 and not have detonation. Not only do you need to keep an eye out for octane, but make sure your getting it from a quality station. Theres a reason some stations cost more.