Gasoline is the most common fuel for vehicles. It is a fuel mixture that is derived from a crude oil with a complex composition. Gasoline varies in many categories and has been used since the beginning of the twentieth century. Nowadays the gasoline quality is dozens of times better compared to the first types of fuels. The given article will provide the insight into the gasoline and its production process and will disclose the term “gasoline additives” and its purposes.

What is Gasoline?

Gasoline (or petrol) is a flammable mixture of light hydrocarbons with a boiling point interval of 33 to 205 °C (91,4 to 401 °F). Gasolines are used as a motor fuel and raw materials in industrial organic syntheses. This fuel mixture is produced from a crude oil and has a complex composition. A gasoline composition can comprise several heavy and light oil fractions and oxygen compounds. Moreover, different proportions of hydrocarbons and impurities also vary. To determine the gasoline quality, physical and chemical properties have to be measured. Gasoline varies in many categories and has been used since the beginning of the twentieth century.

Fuel fabrication from crude oil is a complex multi-stage technological cycle. After a determination of the elements and compounds concentration, the oil is sent to the production process of multistage purification, distillation, cracking at high temperatures and reforming. The certain octane rating gasoline is produced after the mixture processing in a gas fractionator. The isobutane and propane-butane content is adjusted on this stage.

A final product, that is used to car fueling, contain not only the refined oil but also some gasoline additives. These gasoline additives vary from one company to another one and serve to improve gasoline properties.

Octane rating is the major characteristic of gasoline. Octane rating (or octane number) characterizes a fuel’s ability to endure compression in an internal combustion engine without detonating. The higher the octane rating, the more compression the fuel can endure before detonating. Octane rating does not relate directly to the power of the fuel, but simply indicates gasoline’s capability against compression. Certain standards are needed in order to compare the different fuels with each other. The substances n-heptane and iso-octane were chosen for this purpose where the detonation resistance of n-heptane was assigned a value of “0” and iso-octane a value of “100”. In recent time gasoline with higher detonation resistance has been obtained. Interested fact that an extended scale was accepted where the mixture of iso-octane with tetraethyl lead or toluene was taken as a reference in order to characterize these new fuels. Motor gasoline is a multi-component mixture of organic substances so the octane rating is mainly determined by the gasoline composition. A minimal detonation resistance is a characteristic of the so-called “normal” hydrocarbons with a linear structure. A high octane rating is a characteristic of hydrocarbons with branched and cyclic chain structure. The petrochemical industry uses catalytic cracking and reforming processes to produce high-octane gasoline. In such gasoline compositions, the number of hydrocarbons with branched and cyclic structures are increased. The octane rating is also highly reliant on the specialized additives presence, which are so-called “additives” in the fuel.

What are Gasoline Additives?

Gasoline additives are divided into four types: detergents (clean the car injector and the fuel system), absorbents (remove moisture from the fuel), octane boosters (increase the octane rating) and multipurpose additives (usually combine the properties of all the additives mentioned above). A gasoline additives application does not always lead to the desired result and, moreover, can damage the engine and/or fuel system sometimes.

Detergent Additives

A gasoline cleaning additives or detergents are designed to remove carbon deposits and resins from the engine fuel system parts surfaces and an injector. Over time, fouling is formed even while a highest quality fuel is used. Gasoline additives, that clean the fuel system, are recommended for use only as a preventive measure. If a car covers a significant distance (over 60 000 miles / 96600 km) without the fuel system flushing, there is an engine damage risk during an flushing additive utilizing. In this case, the soot flakes off the working parts surfaces during the additive chemical composition action and then gets into the fuel. Large particles may completely or partially damage the injectors.

Absorbents (desiccants)

These compositions are designed to remove moisture from the fuel. Water can get into the fuel in different ways. For example, as condensation on the walls of the gas tank and/or during refueling at negative temperatures. It is worth reminding that water in fuel is very dangerous. It is destructive for the engine and, moreover, can freeze up, that leads to damage of fuel lines or the filter screen.

Fuel desiccants consist of alcohol 80 – 90% and other different chemical absorbing compounds. Before to buy a desiccant additive, it is important to understand that these additives are ineffective. It means that they are able to remove only a small amount of moisture from the fuel (maximum up to 1%). Moisture absorbents can be used only as a preventive measure. If the refueling was done with low-quality gasoline with high water content, it is absolutely necessary to drain it out. Otherwise the engine can be subjected to water hammer.

Octane Boosters

These additives serve to increase the octane rating of a gasoline, also known as fuel catalysts or octane correctors. In addition, according to the manufacturers, they can reduce fuel consumption and increase engine power. Almost all of them consist of monoatomic alcohols, ethers and carbon allotropes. In other words, they contain the same components as the modern 92 and 95 gasoline. An addition antiknock agent makes sense in case the low-quality gasoline was refueled only. But if it happens, it is better to drain out the tank with bad gasoline, rinse the fuel system and refuel it with a high-quality one.

There are two octane boost additive groups: allowed and prohibited. Allowed additives may consist of either MTBE (methyl tret-butyl ether) or MMA (monomethylaniline).

Among the prohibited additives, TES (tetraethyl lead) is the most commonly used that makes exhaust fumes more toxic. Also, ferrocene, that is known as an iron-containing additive, can be used as an antiknocker. It forms a conductive deposit on the spark plug surface while burning that leads to insulator breakdown.

Multipurpose Additives

Usually, these products characteristics are just only marketing ploy with rare exceptions. The same composition cannot successfully rinse the fuel system, increase the octane number and remove moisture. That is why they are not recommended for purchase.

As it can be seen from this article, gasoline additives are not a solution to any problems. However, if to understand gasoline additives composition and maintain the engine regularly and the fuel system, it could prolong the engine lifetime.