If you live in the States, this is probably everything you needed to know about gasoline (and them some). Information is Courtesy of the United States Department of Energy
Types of Gasoline Available in the United States
Definitions of Gasoline Formulations
Finished motor gasoline - : A complex mixture of relatively volatile hydrocarbons with or without small quantities of additives, blended to form a fuel suitable for use in spark-ignition engines. Motor gasoline, as defined in ASTM Specification D 4814 or Federal Specification VV-G-1690C, is characterized as having a boiling range of 122 to 158 degrees Fahrenheit at the 10 percent recovery point to 365 to 374 degrees Fahrenheit at the 90 percent recovery point. "Motor Gasoline" includes conventional gasoline; all types of oxygenated gasoline, including gasohol; and reformulated gasoline, but excludes aviation gasoline. There are three main types:
- The most widely available, it is sold where air quality
is satisfactory. It isn't the same "conventional" gas that was used a decade ago, however. Since 1992
, conventional gas has been formulated to evaporate more slowly in hot weather, thus reducing smog
. It must also contain detergent additives to reduce engine deposits.
Conventional area: Any area that does not require the sale of reformulated gasoline. All types of finished motor gasoline may be sold is this area.
Finished motor gasoline formulated for use in motor vehicles, the composition and properties of which meet the requirements of the reformulated gasoline regulations as stated by the U.S Environmental Protection Agency
under Section 211(k) of the Clean Air Act
. Most RFG uses methyl tertiary-butyl ether (MTBE) as an oxygenate. There are three types:
Standard Reformulated Gasoline
Since January 1995, this gas has been mandated in areas where toxin
s in the air are a constant problem. It also contains oxygen
-rich chemicals but in lesser concentrations than the winter
-oxygenated gas. It also is designed to reduce certain toxic chemicals found in conventional and winter-oxygenated fuels. It's termed Federal Phase I fuel and was replaced in 1999
by Federal Phase II.
Oxygenated Reformulated Gasoline
A wintertime fuel exclusive to the New York City area where heavy carbon monoxide pollution occurs. In the summer, regular reformulated gas is used.
California Phase 2 Reformulated Gasoline
This gasoline, introduced in June 1996, has a different formulation and burns cleaner than regular reformulated gas. In March 1999, Governor Gray Davis issued Executive Order D-5-99 ordering that the MTBE in California RFG be phased out, with none of the oxygenate in the fuel by December 31, 2002. This was because of concerns over MTBE contaminating ground water supplies.
Introduced in 1992, this fuel is sold where carbon monoxide from car exhaust is a problem. It's a conventional fuel with oxygen-rich chemicals added, such as MTBE (methyl tertiary-butyl ether) or ethanol, grain alcohol. The oxygen promotes cleaner burning, reducing carbon monoxide. In areas where oxygenated fuel is mandated, this gas is generally sold from November to March because cold engines run less cleanly and produce more carbon monoxide. In summer, conventional gasoline is used in most of these areas.
A blend of ethyl alcohol (ethanol - CH3CH2OH) and gasoline, usually in a 10% ethanol to 90% gasoline mixture. Ethanol is a liquid that is produced chemically from ethylene or biologically from the fermentation
of various sugar
s from carbohydrates
found in agricultural crops and cellulosic residues from crops or wood. it is used in the United States as a gasoline octane enhancer and oxygenate, it increases octane 2.5 to 3.0 numbers at 10 percent concentration.
The term "gasohol" was used in the late 1970s and early 1980s but has been replaced in some areas of the country by terms such as "E-10, "Super Unleaded Plus Ethanol," or "Unleaded Plus."
Definitions of Gasoline Grades
(classification of gasoline by octane ratings)
Each type of gasoline (conventional, oxygenated and reformulated) is classified by three grades - Regular, Midgrade, and Premium.
Note: Gasoline sales are reported by grade in accordance with their classification at the time of sale. In general, automotive octane requirements are lower at high altitudes. Therefore, in some areas of the United States, such as the Rocky Mountain States, the octane ratings for the gasoline grades may be 2 or more octane points lower.
Regular Gasoline: - Gasoline having an antiknock index, i.e., octane rating, greater than or equal to 85 and less than 88. Note: Octane requirements may vary by altitude.
Midgrade Gasoline - : Gasoline having an antiknock index, i.e., octane rating, greater than or equal to 88 and less than or equal to 90. Note: Octane requirements may vary by altitude.
Premium Gasoline: - Gasoline having an antiknock index, i.e., octane rating, greater than 90. Note: Octane requirements may vary by altitude.