|  | Why should I use your premium gasoline (91-93 octane) instead of regular (87) or midgrade (89)?
To find out what octane your engine needs, first check your owner's manual. The recommended level is often 87 octane. Some models have high compression engines which are designed to utilize the octane levels of 89, 91 or higher.
Ordinarily, your vehicle will not benefit from using a higher octane than is recommended in the owner's manual. But if your engine knocks or pings at the recommended octane level, you may need a higher octane gasoline to prevent the knock. Knocking may occur under certain conditions. A small percentage of vehicles may knock because of variations in engines of the same model due to manufacturing tolerances, or because of an unusual build-up of engine deposits during the first 15,000 miles of driving. Other factors such as extremely hot weather, changes in altitude or hard driving conditions (like towing a heavy load) may also cause knocking.
Many modern vehicles are equipped with an electronic device that detects and eliminates light knocking before you hear it. The devices suppress knock by retarding the spark. We believe that some of these vehicles may experience some deterioration of acceleration performance, without knocking, when operating under high engine demand conditions.
Of course, our gasolines have had very effective detergents for several decades. And, because detergent additives help maintain an engine's emission performance, the EPA has required a minimum dosage in all gasolines since 1995. So, while all gasolines now contain detergents, all our gasolines contain additional quantities to better guarantee fuel system cleanliness.
What is Reformulated Gasoline?
Reformulated gasoline (RFG) is a special blend designed to reduce harmful automotive emissions. RFG must be marketed in those areas of the United States where air quality doesn't meet the ozone requirements of the Clean Air Act Amendments. It is formulated to release fewer volatile organic compounds (VOCs) and has a lower benzene content.
For more information on RFG, visit the API's web site.
What is California Cleaner Burning Gasoline?
California CBG is a type of reformulated gasoline designed to reduce emissions. It reduces the emissions of NOx and volatile organic compounds, has lower benzene and sulfur levels, and limits the amounts of aromatic and olefinic compounds in the blends. It is required throughout the state of California.
For more information on California CBG, visit the California Air Resources Board web site.
Do your gasolines contain MTBE?
ExxonMobil does not use MTBE in our gasolines in the United States.
Do your gasolines contain Ethanol?
In many areas of the country, oxygenates are required to be part of the gasoline formula. In those areas, our gasolines will contain ethanol, which is classified as an oxygenate [US Fuel Requirements Map]. Ethanol is also used in California Cleaner Burning Gasoline and the Reformulated gasolines required in many of the major metropolitan areas of the country. In addition, to meet the Renewable Fuels Standard included as part of the Energy Independence and Security Act of 2007, ethanol blends will be introduced to many more areas of the country over the next few years..
Do your gasolines contain Methanol?
Methanol is not used as an oxygenate in our gasolines.
Do your gasolines contain MMT?
In the United States, our gasolines do not contain MMT.
Do your gasolines meet the World-Wide Fuel Charter?
The World-Wide charter, formerly known as the AAMA Gasoline Specification, has been proposed by many of the automobile manufacturers. To this point, however, the need for the more costly fuel has not been adequately demonstrated, so the specifications have not been adopted by ASTM where auto/oil/consumer consensus specifications are developed. Our gasolines meet ASTM D 4814, Standard Specification for Automotive Spark-Ignition Engine Fuel, as well as all federal, state and local legal requirements. Use of our gasolines will not void your vehicle’s manufacturers' warranties.
Do your gasolines contain detergents?
All our gasolines contain effective detergent additives. While the EPA has required all gasolines marketed in the United States to contain detergents since 1995, our gasolines contain significantly more than the minimum dosages required to provide additional protection against fuel system deposits.
Does gasoline really need detergents?
Yes! Detergents are added to gasoline so that it can help clean and protect your vehicle’s fuel delivery system, including the carburetor or fuel injectors, intake valves and intake port areas. A gasoline detergent is a lot like a household detergent, helping to prevent any harmful deposit build-up.
In fact, it's been proven that due to gasoline detergents, engines
- run smoother
- have better fuel economy
- hesitate less
- have lower exhaust emissions
Gasoline detergents can do such a great job at keeping critical engine components clean that the Environmental Protection Agency (EPA), through the Clean Air Act, has required them to be added to all gasolines since 1995.
How long can gasoline be stored?
There is no single answer to the question of how long gasoline can be kept in storage, because the answer depends upon the conditions under which it is stored. Gasoline in storage can change in two primary ways. It can lose light ends (volatile components) and/or it can oxidize. In addition, gasolines blended with ethanol can absorb water and separate into a gasoline layer and another water/alcohol layer.
Gasoline should generally be used within a month of purchase. When the engine will not be used for an extended period of time, the conservative approach is to drain the fuel tank and then run the engine until it stalls. If you choose to store gasoline, keep it in very nearly full (minimizing air contact) tightly sealed metal containers (minimizing the loss of light ends and the availability of humid air) in a cool environment (slowing down the rate of oxidation). Be sure to leave some room in the container to allow for some expansion. Under these conditions, the gasoline would be expected to remain of good quality for at least 6 months.
What steps do you take to ensure the quality of your fuels?
We have stringent quality control procedures to help protect our fuels at every step of the process.
- We conduct thorough tests on the fuel at the refinery to ensure that it meets or exceeds engine builder and industry specifications.
- We test it again as it enters the pipeline or barge for delivery to the terminal, and then once more as it arrives at our terminal.
- Our proprietary additives are precisely injected as each delivery truck is filled at the terminal, guaranteeing that the gasoline will exceed all performance standards and provide additional benefits to you, our customer.
- At the service station, our drivers and dealers check it once more to ensure that it hasn't become contaminated with water.
And we don't stop there. Once our fuels have been delivered, we survey them at our stations to confirm that:
- our Reformulated gasolines meet all federal standards.
- our gasolines meet state and other locally specified limits.
- our gasolines contain the proper type and amount of our detergent additives.
What is the importance of a gasoline’s antiknock quality?
Antiknock, also known as octane rating, is the measure of a gasoline's ability to resist knock or ping during combustion. The higher the octane rating, the greater the engine's resistance to knock or ping. The knocking or pinging in your engine occurs when the air/fuel mixture detonates prematurely. Since it is the gasoline vapor that ignites, the air/fuel mixture must be correct to burn smoothly. Some of the problems associated with knock are overheating of engine parts such as valves, pistons and spark plugs.
Car manufacturers will specify, in the owner's manual, a minimum octane to be used with their automobiles. Ordinarily, your vehicle will not benefit from using a higher octane than is recommended in the owner’s manual. But, if your engine knocks or pings at the recommended octane level, you may need a higher octane gasoline to prevent the knock.
What does a gasoline’s volatility mean to me?
Volatility is the rate at which gasoline vaporizes at a given temperature. The volatility of a gasoline is important because the liquid gasoline must be mixed with air and vaporized in order to burn in the engine. Liquid gasoline will not burn.
The volatility characteristics of our gasolines are important to your driving performance. Gasoline with high volatility vaporizes more readily than one with low volatility. In hot weather, gasoline that is too volatile can cause vapor lock and stalling in your vehicle. In cold weather, a gasoline that is not volatile enough may cause hard starting and poor warm-up. In the winter months, for example, your vehicle's engine is extremely cold before startup, and the gasoline must have a high enough volatility to be able to vaporize easily in a cold engine environment. Our gasoline’s volatility is carefully balanced on a seasonal and geographic basis, to provide the correct vaporization characteristics to ensure proper operation in your vehicle.
Do your gasolines meet U.S. emissions standards?
Absolutely. Our gasolines meet all federal and state requirements applicable in the areas they're marketed.
In 1963 Congress passed the Clean Air Act, which set in motion a series of changes to automobile design and fuel formulations. Initial changes occurred to engine designs, but in the 70s, fuels were impacted by the requirement to remove lead antiknock compounds. Other changes have followed, notably the requirement to have oxygenated gasolines in carbon monoxide non-attainment regions in the early 90s and reformulated gasolines in severe non-attainment areas in the mid-90s. In addition to these federally mandated changes, many states have also required changes to the fuels.
The impact of all these changes has been dramatic, with air quality showing significant improvements even while the miles driven have increased substantially.
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