When considering whether to prefer 95 or 98 gasoline, you must not forget about the octane number. The number does not indicate the quality of the fuel, but indicates for which engines it is intended. The difference is that 80 octane gasoline is used in cars with engines that have a low compression ratio. Therefore, it is logical to conclude that 98 is intended for engines that require high knock resistance of fuel - highly boosted ones.
Features of the production of 98 gasoline
Before talking about which gasoline is better than 95 or 98, whether mixing them is allowed or not, it is necessary to understand the peculiarities of producing fuel for refueling cars.
The idea that gasoline with an octane rating of 92 and higher is immediately obtained from petroleum products is erroneous. If we do not take into account the technological component, the AI production process can be simplified in two ways:
- The old method is similar to the process of producing moonshine, when, during direct distillation of petroleum products, light fractions are evaporated, followed by their condensation. But this method does not allow obtaining AI 98 gasoline. Even the use of additives will not help, because the resulting product has a low octane number - from 50 to 60 units, no more. This method is practically excluded today for the production of gasoline.
- The new method is based on thermal or catalytic cracking. Under pressure or as a result of other forms of exposure, petroleum products decompose into various groups of hydrocarbons. This process is technologically much more complicated, but it allows you to obtain a larger product, the quality of which is much higher than in the first option.
With this technique, a higher octane number is achieved: from 70 and even up to 80 units. From these numbers it is easier to rise to the desired indicator, for example, to get 98, while the number of additives is reduced.
A technique that deserves special attention, which is not used in our country, is catalytic reforming. With its help, you can immediately get the result of an octane number of 92. But at the same time, the initial cost of fuel increases. Therefore, for most enterprises this method is unprofitable from an economic point of view.
What is the difference between AI-92 and AI-95 and AI-98
If gasoline labeling at gas stations doesn’t mean anything to you or you think that the higher the number, the better, then this article was created especially for you. It's time to dispel the myths about gasoline once and for all and find out what the numbers on gasoline labels mean, and also find out whether your car will be better off if expensive fuel is poured into it.
Gasoline labeling
Before analyzing gasoline labeling, you should understand why it is needed at all.
How does the engine work? A simplified diagram of the operation of the engine is as follows: gasoline and air are supplied to the engine, the piston moves up and down, approximately at the top point of the piston movement, the spark plug ignites the fuel-air mixture, the burning fuel pushes the piston down. It is important that the fuel begins to burn on time, that is, exactly at the moment when the spark plug ignites it.
If the fuel ignites prematurely, when the piston is still going up, this harms the engine, destroying it. Therefore, one of the important characteristics of fuel is detonation resistance, that is, the ability of the fuel to resist spontaneous ignition. Knock resistance depends on the octane number of gasoline. The octane number is indicated in the labeling: for example, AI-95 has an octane number of 95.
The higher the number, the better
It is a myth. AI-95 gasoline is not at all better than AI-92, they are just different and created for different engines. Some engine models have a lower compression ratio and the risk of detonation is lower, so lower octane gasoline, AI-92, is suitable for such engines. In other engine models, the compression ratio is higher, or the fuel mixture may be more enriched with oxygen due to the turbine, which increases the final compression in the cylinder, as a result, the risk of detonation also increases, so these engine models require fuel with a higher octane number to avoid this.
Therefore, thinking that AI-95 gasoline is better than AI-92 is as logical as thinking that absinthe is better than vodka, because it contains 70 degrees versus 40. The quality of gasoline is not characterized by its octane number. It is not the brand of gasoline that characterizes the content of sulfur, manganese and other impurities, but the technical regulations. Therefore, you should not assume that 95 gasoline is cleaner and higher quality than 92: the quality of both brands of gasoline meets modern fuel requirements and current standards.
Higher octane number is better for the car
When oil is directly distilled, gasoline is obtained not at all with the octane number that the end buyer sees, but only 42 - 58. That is, of low quality. Why is this, you ask, isn’t it possible to immediately distill good quality gasoline with an octane rating of 92 and 95? It's possible, but it's expensive. A liter of fuel in this case will cost much more than it does now. The production of such fuel is called reforming. Only 40–50% of the total volume of gasoline is produced in this way (and mainly in Western countries). The second technology for producing gasoline is called hydrocracking or catalytic cracking. Gasoline with the second method is less purified and has an octane number of 82 - 85.
In order to increase the octane number in the second approach, they resort to various additives:
- additives based on metal-containing compounds (for example, tetraethyl lead). Conventionally, they are called leaded gasoline. Such additives are very effective and make the engine work at its best. But such additives are very harmful. As the name suggests, such additives contain metal, namely lead, which, when burned, forms gaseous lead in the air, which is very harmful.
- more advanced additives based on ferrocene, manganese, nickel, but most often monomethylaniline (MMNA). These additives are mixed with gasoline, bringing the mixture to the desired octane number. But such additives are also not ideal; they form deposits on spark plugs, pistons, and clog sensors and catalysts. Therefore, sooner or later, such gasoline will lead to engine blockage (in the literal sense of the word).
- the third type of additives is alcohols and ethers. The most environmentally friendly additives that do not harm the environment. However, these additives also have a drawback - the low octane number of alcohols and esters is only 120 points. Therefore, to achieve the required octane number in gasoline, it is necessary to use more of these additives (about 10 - 20%). Another drawback is the aggressiveness of ether and alcohol additives. At high levels, they quickly corrode plastic and rubber pipes and sensors. Therefore, the volume of such additives in fuel is limited to 15%.
In fact, the difference between AI-92 and AI-95 is minimal, so most likely you won’t even notice the difference. Moreover, AI-95 gasoline contains more additives. And the question is which ones? Poor quality additives in large quantities can significantly shorten the life of the engine. The quantity and quality of additives completely depend on the integrity of the manufacturer; there are no strict regulations in Russia that control the percentage of additives added. Therefore, by filling your car with 95 gasoline instead of 92, you will gain practically nothing, and without knowing the quality of the fuel, you are playing Russian roulette.
Nowadays, basically all manufacturers use the third type of additives - ethers, since esters have a lower combustion temperature, which allows you to save a little fuel when filling with 95 gasoline compared to 92, while the exhaust will be more environmentally friendly.
As for the myth about valves burning out and so on, this will not happen. This was typical for leaded gasolines containing metal additives. High-octane gasolines with such additives could harm the engine. But now there is no such problem, just as there is no such gasoline.
In practice, gasoline is different at different gas stations; you need to find a good fuel manufacturer and refuel from him. There are many gasoline tests on the Internet from different gas stations. In some tests, when analyzing 92 gasoline, it was revealed that this is not the same gasoline as stated, and its octane number is only 76.9! And this is what motorists pour into their cars, trying to save money by refueling at left-hand gas stations with unknown names or without one at all. And then they go to the service center to flush the engine or undergo major repairs.
Compression ratio
The compression ratio is understood as the ratio of the volume of the cylinder space above the piston when the piston is positioned at the bottom dead center to the volume of the cylinder space above the piston when the piston is positioned at the top dead center.
Increasing the compression ratio requires the use of fuel with a higher octane number (for gasoline engines to avoid detonation). In general, increasing the compression ratio leads to an increase in internal combustion engine power and helps reduce fuel consumption.
Relationship between compression ratio and octane number
- 92 – 10,5;
- 95 – 10-12,5;
- 98 – 12-14,5;
- 102 – 13,5-16;
- 109 – 15,5-18.
If the compression ratio is below 10.5, AI-92 gasoline should be filled.
If the compression ratio is from 10 to 12, it is not lower than AI-95. In this case, the volume of the combustion chamber is made specifically for such fuel. AI-92 can be filled in, but it is not advisable.
If the compression ratio is 12 or higher, it is not lower than AI-98.
AI-102 and AI-109 - for compression ratios from 14 and from 16, respectively.
Important! Don't confuse compression ratio with compression.
Different methods for determining octane number
Another problem for an inexperienced car owner is different methods for determining the octane number and, accordingly, different designations of suitable gasoline for a particular car. Basically, difficulties arise due to the difference in the American and European systems.
In short, the systems for labeling fuel by octane number differ: in the USA, Brazil, Canada and some other countries, gasoline is labeled according to the “anti-knock index”, and in Europe - according to the research method. The Russian abbreviation AI means “automobile” gasoline and is determined using a research method. The abbreviation AKI “anti-knock index” is the arithmetic average between two results calculated using two methods for determining the octane number (motor and research). The AKI value is lower than that of the research method. That is, AKI 91 is not at all the same as AI-92.
Approximate correspondence between Russian AI and foreign AKI:
- AKI 87 – AI-92;
- AKI 91 – AI-95;
- AKI 93 – AI-98;
Therefore, when purchasing a car, be sure to look at what is written on the gas tank cap and study the operating instructions so as not to make a mistake in choosing fuel.
“Branded” fuel or regular
Another question regarding fuel is whether it is worth overpaying for “branded” gasoline at large gas stations. In order to understand this issue, you must first understand what causes the price increase: this is not an abstract increase in quality, but primarily the addition of detergent additives. These additives do not affect the quality of the engine, but its relative “cleanliness” for the engine. These additives prevent the formation of deposits in the fuel system. But given that gasoline itself is pure and is an excellent solvent, these conditional deposits will not clog the fuel system in a month or even a year. Therefore, there is absolutely no need to overpay for “branded” fuel with cleaning additives. This action will not give an immediate effect, but rather has a preventive effect.
Conclusion: the choice of octane number depends on the engine model and fuel quality. In the best case, you should fill in gasoline according to your passport. If you want to save money, then you need to first calculate what will be more economical in the end. And also the possibility of such savings.
Important! A turbocharged engine “eats” only gasoline according to its passport.
Most foreign cars have a compression ratio of up to 10.8, so AI-92 is poured into them and there are no problems (of course, provided that the gasoline is of high quality). In winter, the engine on the AI-92 starts at lower temperatures.
Remember that the main cause of engine clogging, detonation and other problems is low-quality fuel. Choose your dressing wisely.
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When does it make sense to fill up with 98 gasoline?
Taking into account European standards, fuel with an octane number below 95 does not exist today. Therefore, when considering whether it is possible to use 98 instead of 95, all that remains is to correctly assess the situation and take into account the recommendations of the car manufacturer.
If these are cars with a turbo engine, and the instructions contain a “fork” of 95-98, then for everyday driving you can use 95. In hot weather, it is better to give preference to AI-98. The explanation is simple: an increase in temperature increases the likelihood of detonation. In this case, it is more useful to use gasoline, which has a higher numerical indicator.
Another dilemma that motorists have to solve is whether it is possible to fill in 98 and 95, i.e. mix 2 types of fuel. Everyone approaches this situation subjectively. It all depends on the situation and several parameters:
- the car itself.
- his engine.
- equipment.
- available electronics.
The gasoline that is chosen for refueling will also play a significant role. Moreover, the engine of one car will behave adequately, but another will not like this mixture. And anything can happen - from valve burnout to problems that require repair of the internal combustion engine.
So you should think carefully about whether to mix 2 types of fuel or whether it’s better not to take risks, but to find a gas station that always has proven, high-quality fuel.
It is best to follow the car manufacturer's recommendations. And if the operating instructions say that you can only fill the car with 95, then there is no need to violate it. If the car is adapted for any type of fuel, then be guided by the situation.
Within the city limits, powerful and turbocharged cars can be filled with 95, but for a long trip on the highway, you should give preference to high-quality AI-98. Driving on the highway will vary in speed.
What kind of gasoline should I fill up with? Manufacturer's recommendations
The first thing I want to draw your attention to is the recommendations of the manufacturer of your car. Most often, the type of fuel your car should consume is indicated on the gas tank flap.
If you do not find a similar inscription on the gas tank flap in your car, you should refer to the instruction manual. In it you will definitely find the recommended type of fuel for your car. By the way, if your car is not of domestic production, then you may not find the familiar A91 or A96 there. Don’t be scared and don’t rush to sell your car, it’s just that the country that produces your car has slightly different standards. And by the way, by indicating a specific brand of gasoline, the manufacturer calls for refueling the car with a brand of gasoline with no lower octane number. For example, A-91 is indicated on your gas tank flap, this means that you can easily fill the car with both 92 and 95 gasoline.
Of course, the manufacturer categorically does not recommend refueling the car with gasoline with a lower octane number. They justify this by the incorrect operation of the ignition system and the engine in general. Operating a car on the wrong fuel can damage it, every manufacturer is sure.
Some cars have an “Octane Corrector”. This regulator allows you to independently select the brand of fuel. Those who have such a corrector note that when changing it from 92 to 95 gasoline, the car becomes faster and more responsive, but at the same time the car became more voracious. Most often, this “adjustment” can be found on cars produced before 2000.
Octane corrector
If you are satisfied with this answer to the question in the title of the article, then you can safely read the next one. But personally, I was not satisfied with this answer when I asked this question. So let's move on.
What engine characteristics does 98 gasoline improve?
It should be noted that the higher the detonation resistance, the slower the combustible mixture burns and the higher the efficiency of the process and its efficiency. This means that the engine will run smoother and the power and efficiency indicators will improve slightly. In reality, engine performance improves by 5-7%, which is not bad at all.
Quite often, many owners claim that the high octane number of gasoline is achieved through additives containing lead and sulfur, which have a detrimental effect on the fuel system and engine. Indeed, for a long time, the octane number of gasoline was increased with the help of tetraethyl lead, the use of which in minimal doses raised the octane number by 20 units. But modern environmental requirements almost completely eliminated this additive from use about 10 years ago. Instead of tetraethyl lead, they began to use metal-containing additives - ferrocenes, which have low cost and good efficiency. The use of gasoline with ferrocenes leaves a conductive coating on the catalyst and spark plugs, which turn bright red. Gasoline with such additives is not sold at gas stations owned by well-known companies, but is quite often found at “leftist” gas stations.
The latest invention in this area is the use of alcohols and ethers. There is no harm from them, but the effect is quite high.
It should be noted that the detonation resistance of gasoline is not a constant number, and if 95 gasoline has the maximum value, and 98 gasoline has the minimum, then the characteristics of these grades will be as close as possible to each other and, when refueling from such batches, you will feel changes in the behavior of the car will be almost impossible.
Features of 92 gasoline
AI-92 is intended for carburetor internal combustion engines. Such engines operate at a higher compression ratio. Gasoline provides fairly high protection against detonation and smooth operation of the mechanism. It is of normal quality and contains anti-knock additives. Now this fuel is no longer produced in the eurozone countries, but in the cities of Ukraine and Russia it is still as popular as before. Popular among owners of cars with injectors. It comes in leaded and unleaded. The difference is in the amount of lead.
What is 95-Ekto and what are the differences from Euro
Before you find out what the difference is between 95 and 95 Ecto, you need to find out what it is.
It is worth noting here that this type of gasoline also complies with the Euro-3 standard, which means that all the characteristics described above apply to this gasoline. Moreover, the environmental performance has been improved: the sulfur and benzene content has been reduced several times, so we can say that the Ecto brand is an improved version of the Euro-3 standard. However, this is not the only difference. The main characteristic of this fuel is the use of special additives designed to increase the service life of the engine and other key components of the car.
The main characteristics of 95-Ecto gasoline, which distinguish it from 95-Euro, are listed below:
- increasing the reliability of the power unit, as well as extending the service life;
- the ability to use maximum vehicle power;
- the presence of specialized additives protects key components from corrosion;
- reduced detonation levels, resulting in quieter and quieter operation;
- increasing the service life of the injection system;
- minimizing precipitation and reducing fuel consumption.
The same properties apply to the characteristics of Ecto diesel fuel from Lukoil. According to the developers, the use of the Ecto brand allows reducing fuel consumption by almost three and a half percent. The presence of detergent additives significantly reduces the amount of plaque, which makes the operation of the power unit quieter.
At gas stations, 95 Euros from 95 Ecto also differs in cost. The differences are insignificant, but on average amount to several rubles.
