Although all types of gasoline are sourced from oil, the specific treatment and chemicals added to the oil is what determines particular purpose and grade. Using the proper fuel grade in your automobile helps to ensure its efficiency and protect the motor from detonation.
The following information will help you understand the differences between the available grades of fuel. There are currently three primary grades of fuel available in the U. The best fuel grade for your vehicle is based on its particular manufacturer, so there is no gain to using premium gas if the maker specifies regular.
Regular, plus, and premium fuel grades are all distinguished by how much octane they contain. There are different ways of measuring octane ratings, and the U. According to the Federal Trade Commission , regular gasoline is usually 87 octane, mid-grade is 89 octane with premium usually being at 92 or 93 octane. If you are ready this anywhere in Wyoming or even Denver, you might be pondering right now. Those are not the choices you are most likely to see at your local gas station.
I called the Wyoming Dept of Agriculture and they told me that 85 Octane is the legal minimum octane rating for motor fuel in Wyoming. I asked them why that was and the reply was… altitude. He referred me to an ASTM publication but told me the information was proprietary. Air is less dense at altitude. The cost increase is typically higher than the fuel savings. However, lowering CO 2 emissions and decreasing petroleum usage by even a small amount may be more important than cost to some consumers.
The sale of 85 octane fuel was originally allowed in high-elevation regions—where the barometric pressure is lower —because it was cheaper and because most carbureted engines tolerated it fairly well.
This is not true for modern gasoline engines. So, unless you have an older vehicle with a carbureted engine , you should use the manufacturer-recommended fuel for your vehicle, even where 85 octane fuel is available.
Ethanol has a much higher octane rating about than gasoline. Refiners usually blend ethanol with gasoline to help boost its octane rating—most gasoline in the U.
Ford Motor Company. Szybist, J. SAE Int. Fuels Lubr. Stein, R. Polovina, K. Roth, M. Foster, et al. Leone, T. Olin, J. Anderson, H. Jung, et al. Kalghatgi, G. All gasoline is derived from crude oil , formed from the remains of plants and animals held under great pressure for millions of years, which has a mixture of both long chain and short chain hydrocarbons.
How the oil is treated and processed at a petroleum refinery will determine the grade of gasoline fuel. The process by which these different products are recovered is called fractional distillation. Here, crude oil is pumped into a furnace and heated at high temperatures over degrees Fahrenheit, degrees Celsius.
Most hydrocarbon molecules evaporate and rise into a fractioning column. As the evaporated molecules rise up this or more foot-tall column, the heavier molecules will condense at the lower levels, and the lighter hydrocarbons will be at the higher levels. A gallon barrel of crude oil can be converted to about 20 gallons of motor gasoline, 12 gallons of distillate fuel diesel , 4 gallons of jet fuel and other products. The extra cost of higher-octane gasoline is due to the expense of adding octane enhancers or additional branched or aromatic hydrocarbon fractions.
Lower octane levels can combust easier when compressed, which may make the knocking or pinging sound in an engine. The knocking or pings happen when there is non-uniform combustion causing irregular pressure waves in a cylinder. Standard-performing vehicles are outfitted to use the correct amount of compression to eliminate internal combustion pings.
High-performance cars benefit from premium gasoline because their engines have been built for a higher level of compression for added driving power.
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