You can buy 76 brand 100 oct. race gas for about ~ $35-$40/5 gal tank from local dealers and then mix it with 91 oct and you'll get 93 oct. I don't recall the ratios of 91 to 100 mixture.Klui said:I live in Antioch, California. Does anyone know where to buy gasoline higher than 91 octane? I have been unsuccessful finding a gas station that sells higher octane. Thanks.