Gasoline—a petroleum product
Gasoline is a fuel made from crude oil and other petroleum liquids. Gasoline is mainly used as an engine fuel in vehicles. Refineries in the United States produce about 19 gallons of gasoline from every 42-gallon barrel of crude oil that is refined. Refineries and companies that produce the finished motor gasoline sold in retail gasoline fueling stations may add various liquids so that the gasoline burns cleaner and meets air pollution control standards and requirements. Most of the motor gasoline now sold in the United States also contains about 10% fuel ethanol by volume. This is required by a federal law intended to reduce the amount of oil that the United States imports from other countries.
There are three main grades of gasoline sold at retail gasoline refueling stations:
Some companies have different names for these grades of gasoline, like unleaded, super, or super premium, but they all indicate the octane rating, which reflects the anti-knock properties of gasoline. Higher ratings result in higher prices.
Before 1996, lead was added to gasoline as a lubricant to reduce wear on engine valves. Leaded gasoline was banned for sale in the United States on December 31, 1995. Manufacturers recommend the grade of gasoline for use in each model of a vehicle. However, most gasoline-fueled vehicles will operate on regular gasoline, which is usually the least expensive grade.