Gasoline

Arizona CBG is gasoline formulated specifically for use in Maricopa County and in such a way as to greatly reduce harmful emissions from motor vehicles.  Generally speaking, the use of Arizona CBG combats carbon monoxide emissions during the winter (November thru March) and volatile organic compounds during the summer (April thru October).

Conventional gasoline is a volatile flammable liquid mixture of hundreds of species of hydrocarbons, obtained from the distillation of crude oil, and used as fuel for internal combustion engines.  Generally speaking, conventional gasoline does not contain an oxygenate (an oxygen-carrying chemical compound) and has not been chemically reformulated to meet specific air quality standards, such as in the case of Arizona CBG. Within Arizona, conventional gasoline is primarily used in areas of the state other than Metropolitan Tucson and Maricopa County.

Oxygenated gasoline is gasoline to which an oxygenate (an oxygen-carrying chemical compound), typically Ethanol, has been added. Blending an oxygenate, such as Ethanol, into gasoline promotes a more complete  combustion of the gasoline, which, in turn reduces emissions from the tail pipe of motor vehicles.

The octane number, or more accurately described as Anti-Knock Index (AKI), is a measure of a gasoline blend’s ability to resist engine knock. The octane number is commonly displayed on gasoline dispensers describing regular, midgrade and premium grades of gasoline with numbers such as, “87”, “89”, or “91”, respectively.  Generally speaking, higher octane number gasoline is required in high compression or high performance engines or vehicles, and lower octane number gasoline may be used in low compression or low performance engines or vehicles.

Within the combustion chamber of a spark-ignited, internal-combustion engine, a spark plug ignites the compressed air-fuel mixture (atomized gasoline and air) resulting in a flame which radiates away from the point of ignition and across the top of the piston quickly and smoothly. During this process, should the air-fuel mixture ignite spontaneously, in advance of the flame front, a sudden jump in the pressure occurs within the cylinder which results in the familiar pinging or knocking sound.  There are a variety of causes of engine knock, including using the wrong grade of gasoline in a given application.  Regardless of the cause, engine knock is detrimental to the life of an engine and should be addressed immediately.

Not necessarily. A good rule of thumb is to simply follow the instructions given within your vehicle’s owner’s manual. Your vehicle’s engine was designed in such a way as to run on a specific grade of gasoline; therefore, it is best to follow the manufacturer’s recommendations.

E85 is not gasoline; rather, it is a blend consisting of 85% by volume fuel ethanol and 15% by volume gasoline.  Three classes of E85 exist (Class 1, Class 2 and Class 3), each of which is appropriate for use in specific seasons and geographic locations. In addition, E85 is suitable for use in only flex-fueled vehicles.