Unleaded and leaded gasoline: brands and characteristics. Unleaded gasoline - what is it, how does it differ from leaded

Car owners prefer to use high-quality fuel in their car, recommended by the car manufacturer. This allows you to significantly extend the life of the engine and operate the vehicle safely. It is not always possible to find out exactly the chemical formula of the gasoline that is poured into the tank, but if there are concerns about the quality of the fuel offered, then you should look for another gas station.

Leading: evolution of the phenomenon

Even someone who does not understand chemistry, looking at the name “tetraethyl lead”, can assume that this substance is most likely unsafe. After all, any lead compounds are toxic. Naturally, this additive was no exception. And, by increasing the fuel's resistance to detonation (that is, increasing its octane number), it introduces lead into the exhaust, which easily spreads into the environment. The situation with the use of leaded technology developed as follows:

After its discovery in 1921, the substance was actively introduced by the largest American automobile companies, including General Motors, Standard Oil and DuPont.
By 1950, the use of such fuel had become a de facto industry standard, as manufacturers were impressed that a relatively cheap additive could significantly increase the octane number, and therefore sell their fuel at a much higher price.
Only in 1972, when massive cases of lead poisoning were registered in the United States, and the US Health Association began to record elevated levels of lead in people’s blood, was the cause established - massive emissions of this substance into the atmosphere due to the use of leaded gasoline.
In 1976, a radical decision was made to ban the production of this type of fuel in the United States. Despite the opposition of big business, the solution was nevertheless implemented, and leading was stopped.
Europe took much longer to adapt. It was only in 2000 that leaded gasoline was completely banned, and strict environmental standards for all types of fuel began to be introduced.

After conducting medical research, it was found that the level of lead in the blood of US residents decreased by 86% if we compare the figures in 1976 (when the fight against leaded fuel began) and 2000 (when Europe decided to introduce similar standards).

Therefore, the answer to the question of which gasoline is more toxic is obvious: leaded gasoline was poisonous, but its use is a thing of the past, and today only unleaded fuel is used.

What is unleaded gasoline?

Unleaded gasoline is a fuel that is produced from petroleum by distilling it into different compositions. The resulting gasoline mixture has high detonation characteristics during compression. A critical level of compression provokes self-ignition before a spark occurs from the spark plug. In other words, detonation occurs too early, which increases wear on the pistons and cylinders, loads the connecting rod and piston group, and leads to an increase in temperatures, due to which the engine overheats greatly.

The parameter that determines the compression ratio at which detonation occurs is called the octane number. Gasoline obtained immediately after oil refining has an octane number of 56-60. This fuel is not suitable for a car.

This indicator can be increased by adding special environmentally friendly additives made from alcohols and ethers to the fuel. This type of gasoline is called unleaded. It is safe for the environment and humans, practically does not clog the car catalyst and is actively used throughout the world.

Unleaded fuel comes in different grades, depending on the octane number.

Stamps

Many drivers are interested in the question, what is unleaded gasoline? Ignorance gives rise to many conjectures and rumors that have absolutely no basis. Therefore, it is necessary to carefully analyze this concept in order to clarify all the points and answer questions of interest. But first, we need to give some facts about gasoline.

Main brands of unleaded fuel

Let's consider what brands of unleaded gasoline exist, according to GOST:

AI 80;
AI 92;
AI 95 (ECTO and Euro);
AI 98.

A group of letters indicates that the octane number was isolated by a research method. The numbers express the detonation resistance of the brand.

Also, this Standard identifies several environmental classes of unleaded fuel:

The environmental class determines the level of sulfur and other harmful substances in the exhaust. The higher the class, the cleaner the fuel. For example, eco-class K5, in the same volume of gas cloud, implies 50 times less sulfur than K2. There is no sulfur in unleaded fuel K6. Currently, it is prohibited to produce non-environmentally friendly fuel of class below K5 in the countries that are members of the Customs Union. Branded gas stations from renowned gasoline manufacturers adhere to these standards. But small private networks, as well as some manufacturers from Central Asia, are still “cracking up.”

Remember, when refueling, you have every right to request documents for the fuel poured into the tank. In the technical documentation of any gas station, each brand is designated, by analogy: unleaded gasoline grade AI 92 K5.

Why is leaded gasoline banned in most countries around the world?

To avoid this phenomenon, it was necessary to subject petroleum products to complex and expensive processing technology.

Therefore, manufacturers were looking for a simple and cheap way to increase the octane number.

As a result of experiments, it was found that tetraethyl lead copes best with this task.

What is leaded gasoline?

Leaded gasoline is essentially the same fuel obtained by distilling oil. However, the required octane number was achieved here by adding tetraethyl lead. This additive makes the fuel toxic. Its exhaust contains too much volatile lead, which, settling in a person’s lungs, leads to serious illnesses. The component also harms plants and animals and greatly pollutes the atmosphere. Also, different brands of leaded gasoline have a detrimental effect on the internal components of the car. In particular, on the engine, exhaust system, catalyst.

For the first time, ethyl impurities began to be added to gasoline mixtures in the 20s of the last century at General Motors. The fact that leaded gasoline is poisonous was carefully hushed up. For a long time they did not talk about its toxicity, but several decades later the truth triumphed. Closer to the 80s, such brands disappeared from the shelves of American gas stations. By the 2000s, this also happened in Europe. In Russia, leaded fuel was officially banned only in 2002.

Unleaded gasoline does not contain additives containing tetraethyl lead. It contains alcohol and ether additives that do not destroy the environment. Conversely, leaded one contains ethyl metal-containing mixtures, due to which toxic lead is present in the exhaust. Such brands are prohibited today.

History of origin

Since the beginning of the 20th century, when the automotive industry was just beginning to develop, the issue of fuel detonation in internal combustion engines was quite acute. After all, as a result of primary oil refining, fuel is obtained, which, according to its technical characteristics, is still unsuitable for use, since it has a low octane number.

What it is? This is an indicator that shows the degree of pressure required for detonation. During primary oil refining, the octane number hardly reaches 60, while for most engines it is recommended from 92 (or at least 80). However, the secondary processing that helps increase the octane number is quite expensive and complex.

And manufacturers began to think about the question: how can the degree of detonation be increased in a cheaper way? And such a way was found. In the 20s of the last century, General Motors were able to significantly increase the octane number of gasoline by adding ethyl impurities (tetraethyl lead). Soon they opened their own plant for the production of leaded gasoline.

It was significantly cheaper than usual and at the same time more poisonous, but this fact was hushed up for a long time.

This is exactly how leaded and unleaded gasoline appeared on the American market, and soon in other regions. The price difference was significant. Information about its harm was hidden. Therefore, such gasoline became increasingly popular, and soon almost completely replaced unleaded.

Information that during its production tetraethyl lead, which is harmful to the human body, is added, was hushed up, because we were talking about millions in profits.

The facts of vapor poisoning at the factories that produced it were not made public and were explained by accidents in chemical production.

The situation changed only 20 years later, when the negative impact of leaded fuel on the environment and on humans was first proven. However, it was possible to completely shut down the production of such fuel in America only after another 30–40 years.

Already in the early 80s in America there was a ban on the production of engines running on such fuel; after a few years, leaded gasoline completely disappeared from gas stations.

However, in Europe, a ban on the use of leaded fuel has been in effect since 2000.

Leaded gasoline was banned in Russia only in 2002.

Types and brands of gasoline allowed in Russia

The quality of gasoline, its grades, types, operational and physical and chemical indicators are determined by standards. According to GOST R 51105-97, there are 5 grades: 80, 91, 92, 95 and 98. Moreover, the presence of harmful impurities such as tetraethyl lead, manganese and iron is prohibited in each of them.

That’s why gas stations sell exclusively unleaded gasoline, because both factories and gas stations value their reputation. But if you purchase fuel not at certified gas stations, but from private individuals, you may encounter falsification.

Fraudsters are trying to increase the octane number of fuel on their own by mixing different types of fuel or adding harmful impurities (including those containing lead).

What is the difference between leaded gasoline and unleaded gasoline? At the time when its production was allowed, at the same time as the use of lead, special dyes were added to gasoline, which subsequently served as an indicator. According to international requirements, leaded gasoline had to have a reddish color.

Externally, no other differences were observed. That is why, if there are ethyl impurities in gasoline, today this can only be determined through laboratory research. Or by experience. Indeed, in addition to the negative impact on humans, tetraethyl lead literally “kills” the catalytic converter of the car.

The catalyst consists of a large number of ceramic or metal honeycombs, with the help of which exhaust gases are purified. Once in the catalyst, harmful exhausts are decomposed into harmless and simple substances. Thus, the amount of emissions into the atmosphere is brought back to normal.

Exhaust gases containing lead compounds entering the catalyst will also decompose, but as a result, the honeycomb will soon become covered with a layer of lead and will cease to perform its function.

And replacing a catalyst costs a tidy sum, which can amount to several tens of thousands of rubles, depending on the make and model of the car. In addition, lead renders all engine sensors unusable, as a result of which it also stops working normally or fails altogether.

And a little technology

Why did entire generations of researchers bother so much with the invention, testing, implementation and subsequent improvement of anti-knock additives? The fact is that almost immediately with the beginning of the use of the internal combustion engine in the automotive industry, the question arose about increasing its power. Or rather, specific power: of course, it was possible to increase the engine size, but not indefinitely (besides, the car would become heavier and the additional power would be wasted). Increasing the fuel compression ratio is the main way to increase the specific power of an engine, which almost immediately began to be used by designers. And here the problem of detonation arose: the explosive ignition of part of the fuel mixture upon reaching certain pressure and temperature values in the combustion chamber.

Why is detonation harmful and why did you need to fight it?

It is clear that explosive processes with uncontrolled sharp changes in pressure and temperature negatively affect engine parts: pistons, rings, cylinder walls. Engine operation is accompanied by characteristic sharp knocking noises, and prolonged operation in this mode can lead to serious damage followed by expensive repairs. But that’s not all: during the detonation process, the fuel mixture does not burn completely (an external sign is the appearance of black exhaust from the muffler pipe) and the engine loses power. So instead of increasing the power of the car during detonation, exactly the opposite process occurs. The division of gasoline types according to detonation resistance was proposed back in the 20s of the last century according to a criterion now well known to motorists: octane number. For this, two liquids with opposite detonation abilities, but similar in density and boiling point, were used:

N-heptane—the detonation resistance of a mixture with air is taken as the reference zero for the octane number.
Isooctane - a mixture with air practically does not detonate - the reference index is 100.

The octane number of the gasoline under study is still determined to this day using a setup that includes a single-cylinder engine with the ability to smoothly change the compression ratio. As soon as detonation begins in such an installation during testing, gasoline is replaced with a mixture of isooctane and n-heptane and detonation is achieved by changing the proportion of reference liquids. That is, if the isooctane/n-heptane ratio turns out to be 92:8, then the octane number is 92. In world practice, two methods for determining the octane number are accepted:

research;
and motor.

They differ in more stringent testing conditions using the motor method: the octane number is approximately 9 - 10 points lower than using the research method. Therefore, it is important for the consumer to understand that when purchasing “research” AI 95, he fills the car with “motor” gasoline A 85 or A 86. In a number of countries, for example in the USA, a universal octane number index has been introduced - AKI (Anti-Knock Index), which equal to the arithmetic mean of the “research” and “motor” octane numbers. Therefore, motorists should take into account that fuel with an octane rating of 86 according to AKI, approved for use in American cars, for example, corresponds to our AI 92.

What are the differences between leaded and unleaded gasoline?

To tell the difference between leaded fuel and unleaded gasoline, you need to know how they are produced. When tetraethyl lead is added to low-octane liquids, a toxic substance is formed, but it has high performance characteristics. The result is leaded gasoline. The higher the OC, the lower the risk of detonation (spontaneous fuel explosion).

Unleaded gasoline has a slightly different production technology, as it undergoes additional stages of purification from harmful impurities, including sulfur, lead and their derivatives. It also contains more environmentally friendly additives (aromatic amines, ethyl alcohol, methyl tert-butyl alcohol, ferrocene, etc.). It is unlikely that you will be able to notice the difference without special equipment. Additive standards are regulated by GOST legislation.

Main characteristics of gasoline

To understand what leaded and unleaded gasoline is, you need to start with the basics. It should be remembered that the most important characteristic of any fuel is the octane number. It reflects the maximum degree of compression of gasoline before spontaneous ignition.

Please note: The higher the octane number of gasoline, the higher the compression ratio it can withstand.

The car engine is designed in such a way that maximum power can be obtained if the fuel explosion occurs when the piston is at the top of its stroke. Ideally, it is when the piston is at top dead center that a spark should occur, which ignites the gasoline, after which the piston is sent downward from the explosion.

If a spark is supplied earlier or a fuel explosion occurs due to compression, then the piston stroke length is reduced, accordingly, less work is done and more gasoline has to be spent to cover the distance - the engine uses fuel less efficiently.

To increase the octane number of gasoline, you need to eliminate all kinds of impurities from it. In other words, the fuel needs to be cleaned of various foreign elements, especially sulfur. When producing gasoline, it is purified using special equipment.

Due to the fact that gasoline producers began to use equipment for purification, its cost increased. But engineers from the USA have proposed a solution to make the cleaning process cheaper. To do this, they added tetraethyl lead to gasoline, which is the key component that distinguishes leaded and unleaded gasoline.

Are there additives or additives that can prevent phase separation?

In practice, there are no additives that can prevent phase separation. The only practical solution is to prevent water from accumulating in the tank in the first place. Are there additives that, when added to the fuel tank, will remix the separated mixture? No. The only way to avoid further problems is to remove water, dispose of exhausted fuel, and clean the tank; and then you need to start by using fresh dehydrated fuel.

Is it possible to distinguish gasoline by sight or smell?

First of all, it is worth noting that in all large cities of the Russian Federation, since 2002, the sale of leaded gasoline at gas stations has been prohibited. However, in the outback the situation is far from ideal, so you can easily end up with counterfeit unleaded alcohol or a deadly mixture of two types of fuel.

How can you tell whether gasoline is leaded or not, and is it possible to distinguish gasoline by smell or color? According to existing European and Russian standards, normal unleaded gasoline is a colorless transparent liquid. This can be clearly observed in glass containers (for example, in a jar).

Leaded fuel has a red or orange dye added to it, and the lead content can be smelled. To be more precise, leaded gasoline has a very strong unpleasant odor, which is significantly different from unleaded fuel.

Can you tell the difference by color and smell?

Today, unleaded gasoline is not tinted, and therefore it is problematic to determine the brand by color. How to understand whether a given fuel is leaded or unleaded. Neither the smell nor the consistency will help to make an accurate conclusion. Perhaps ethyl makes the fuel fatty, but it is impossible to judge for sure based on this attribute.

In view of the existing ban, of course, you will be assured that the fuel does not contain toxic metal additives. However, only laboratory analysis will help to verify this for sure.

To protect yourself from low-quality manufacturers and sellers, refuel only at certified gas stations of famous brands. Most of them can already be seen on Yandex maps of gas stations and other applications. Large companies that value their reputation are unlikely to risk their established reputation for the sake of targeted gain.

If you suspect something is wrong, check the spark plugs. Even one consumption of a full tank of leaded fuel is enough for a reddish coating to appear on these elements.

Octane value

Octane number (ON) is the most important characteristic of gasoline, determining the compression ratio at which self-ignition of the fuel (detonation) will occur. In other words, the octane number is determined by the moment when part of the fuel, during compression, ignites not with a spark plug, but spontaneously. Such spontaneous combustion has the nature of a mini explosion. The speed of propagation of the blast wave fluctuates in the range of 1000 – 2300 m/s (with a normal combustion cycle of the air-fuel mixture it is 20 – 30 m/s).

Ways to increase octane number

The octane number can be increased in two ways:

Purification of gasoline from foreign impurities during the production process. This method is technologically more complex; distillation leads to higher prices for gasoline.
Leading is an increase in octane number by adding tetraethyl lead, an extremely toxic substance.

Tetraethyl lead affects the central nervous system, causing hallucinations and panic attacks. The substance evaporates at 0°C and can penetrate the human body even through the skin. If you inhale air with a concentration of tetraethyl lead of only 2% for 2-3 minutes, a person begins to have a severe cough and headache, accompanied by loss of concentration of movement.

The additive causes no less harm to the engine, and exhaust gases harm the environment.

Today, the production of leaded fuel is banned in Europe, the USA and Russia. But, despite the ban, the risk of refueling with “dirty gasoline” remains. Unnamed gas stations are especially guilty of this. In pursuit of customers, they are forced to reduce fuel prices, so they act illegally.

To protect yourself and your car from low-quality and dangerous petroleum products, RusPetrol recommends using TNK fuel cards for legal entities and citizens. The company cooperates only with serious oil refining companies whose products meet all regulatory requirements.

When you refuel at the RusPetrol gas station network, you will always be confident in the quality of your gasoline.

American invention

In 1921, American scientist Thomas Midgley discovered that tetraethyl lead, a toxic organometallic substance, can significantly increase the resistance of even the cheapest gasoline to spontaneous combustion. This discovery interested the three largest US corporations: General Motors, Standard Oil and DuPont. Together they built a plant where they produced tetraethyl lead.

This substance is very poisonous. It evaporates already at 0°C. Once inside the body, it causes damage to the central nervous system and cerebral cortex. Tetraethyl lead can also penetrate into the human body through intact skin. Poisoning is accompanied by terrible hallucinations and panic attacks.

Despite all the dangers of production, the plant operated for many years. During this time, dozens of people died. The lead content in the blood of all US residents, even in 1978, exceeded the norm. Only 16 years later, the terrible production was closed in court at the initiative of the American Environmental Protection Agency.

Danger for cars

Leaded gasoline (containing tetraethyl lead) has a rather detrimental effect on the exhaust gas converter (catalyst), which is provided in almost all modern cars. Sometimes just one refueling with such fuel is enough for the neutralizer to fail. Its failure is directly related to the lambda sensor, which is responsible for maintaining the oxygen level in the exhaust gases.

From this it should be concluded that the use of leaded fuel, even in rare cases, can disable an imported car, since such cars do not work or work poorly with a damaged exhaust gas catalyst.

In addition, when leaded gasoline enters a vehicle, it causes a number of other problems, since the shock waves generated by the detonation of such fuel destroy engine parts.

Detonation can lead to the following consequences:

Heat transfer will increase, which will lead to overheating of the power unit.
The shock wave can destroy the oil film formed on the cylinder walls. This will lead to “dry” friction of the piston group.
The strong pressure (70 kg/cm2) created during an explosion can damage engine parts.

The combination of these phenomena will significantly reduce the life of the power unit and, most likely, will lead to the need for major repairs.

How does leaded gasoline affect your car?

As mentioned above, leaded gasoline is extremely dangerous to human health, and it is almost universally prohibited.
But then the question arises: why do car manufacturers indicate in technical documents for a car that it can only be operated on unleaded fuel? The fact is that leaded gasoline negatively affects the elements of the engine and fuel system. Due to the high lead content in leaded gasoline, when used, oxygen sensors are quickly covered with lead, which leads to their failure. Accordingly, they will not be able to control the process of creating the air-fuel mixture, which will lead to difficulties in engine operation. Also, due to the high lead content, the car's catalyst will quickly fail.

Tetraethyl lead poisoning [edit | edit code ]

Tetraethyl lead is a volatile toxic liquid, which at a temperature of 0° turns into a vapor state and enters the body through the upper respiratory tract. Tetraethyl lead can also enter the body through intact skin. This substance is a strong poison that selectively affects the nervous system, causing acute, subacute and chronic poisoning. The latter are determined by the functional cumulation characteristic of this toxic substance.

More often, poisoning is acute and subacute. The cerebral cortex is primarily affected. In the area of the vegetative centers of the diencephalon, a focus of stagnant excitation arises, which leads to gross disturbances of cortical-subcortical relationships.

Pathogenesis [edit | edit code ]

In the pathogenesis of tetraethyl lead poisoning, a certain role is played by disruption of enzymatic processes, leading to the development of degenerative changes in nerve cells against the background of severe vascular disorders (hyperemia, edema, hemorrhage).

In the development of the clinical picture of acute poisoning (in case of accidental ingestion of leaded gasoline, in case of accidental contact with a large surface of the skin), 3 stages are distinguished - initial, pre-climax and climax.

Does ideal gasoline exist in nature?

Octane is the eighth representative of the simplest hydrocarbons. A liquid, oily substance contained in petroleum that provides ideal parameters for engine operation. Namely, octane is able to withstand high temperatures and does not ignite or detonate during compression. This ensures a high efficiency of the engine. The chemical compound with the formula C8H17 is ideal gasoline.

It would seem, what could be simpler? It is necessary to extract 10 percent of the octane from the processed oil and send it to gas stations, cans, tanks and gas tanks. But it was not there. Octane, containing 8 carbon atoms, felt comfortable in company with other hydrocarbons contained in oil.

But it categorically refused to separate into a separate substance, and disintegrated into compounds with a smaller number of carbon atoms. It was important to bind the molecule so that it contained 8 carbon atoms, more precisely, 8 methyl groups. This is where the term octane number was born. In fact, this number determines the percentage of octane in gasoline. The gasoline released by distillation contained from 30 to 50 percent octane, but this was not enough for the smooth operation of the engine.

Legislative bans on leaded fuel

The fight against the use of leaded gasoline began two decades after the start of its production, when its extremely toxic nature was convincingly proven. Workers in the United States constantly complained of dizziness, nausea and other signs of poisoning.

The use of tetraethyl lead as an octanating agent was banned in the United States only in 1972.
It was not possible to close all production of leaded gasoline in the United States for almost twenty years, since their cheapness paid for all the fines and sanctions.
It was not until 2000 that the production of leaded gasoline was completely stopped in Europe.
In Russia, the production of leaded gasoline was legally banned in 1986, but only in 2003 was the last enterprise that produced it closed.
Currently, only the poorest countries - Yemen, Afghanistan and several other states - have not abandoned the production of leaded gasoline.

The use of unleaded gasoline significantly extends the service life of vehicles. But the most important thing is that exhaust gases cause significantly less harm to human health and do not poison the environment.

The simplicity of producing gasoline with the addition of tetraethyl lead makes it possible to organize its semi-handicraft production almost in a garage. Criminal and semi-criminal elements take advantage of this, then sell their product illegally, at spontaneous sales points, or through a network of distributors. To avoid clogging the exhaust system of your car and premature engine failure, you need to buy gasoline only at proven gas stations, where its quality is guaranteed by the high reputation of the manufacturer and legal requirements.

Impact on crime[edit | edit code ]

According to an influential hypothesis [ which?

], proposed to explain the fluctuations in crime rates in the second half of the 20th and early 21st centuries, tetraethyl lead poisoning in childhood entailed a disruption in the development of the central nervous system, which resulted in an increase in delinquent behavior in adulthood, which led to an increase in crime with 1960s to early 1990s. The fall in crime rates since the 1990s, according to this hypothesis, is explained by a decrease in the consumption of gasoline made with tetraethyl lead since the 1970s [10].

For many motorists, especially those who first got behind the wheel in the mid-2000s, the very concept of “leaded gasoline” is associated only with a sticker on the inside of the gas tank flap and an inscription in English (unleaded only): the production of such gasoline has long been prohibited. Meanwhile, the cheapness and effectiveness of tetraethyl lead still pushes many unscrupulous sellers to distribute it. What is the difference between leaded gasoline and unleaded gasoline and why was it banned for use in many countries? The answers to these questions may be of interest to a wide range of motorists.

Technical regulations requirements for gasoline

When refining oil with subsequent separation of gasoline, the latter must formally comply in quality with the standardized indicators, which are enshrined in the technical regulations. This is a legislative act that prohibits the release into circulation of fuel that does not meet the requirements, and manufacturers are held liable for this.

According to GOST, the main quality indicators are:

Flash point, which should be no more than 100 degrees;
Group composition of various fractions of hydrocarbons;
Must be inert to engine parts made of plastic and rubber;
Detonation activity, which should be in the range of 72-85 for different brands;
The quantitative content of lead compounds (in terms of metal) is no more than 0.013 g/cubic meter. dm;
Resin concentration – no more than 1200 mg/cu. dm.

Excess levels of heavy metals are unacceptable and, if this is detected, the batch of gasoline must be withdrawn from circulation.

The use of fuel containing tetraethyl lead causes a significant impact on human health and the environment. Accumulating in groundwater and the human body, lead can cause severe diseases of the respiratory and circulatory systems, including cancer.