Features of using different octane numbers in gasoline

Mixing gasoline with different octane ratings often causes concern among drivers, especially if the usual type of fuel is not available at the gas station. However, as the auto mechanic explained in an interview with the portal naavtotrasse.ru, such actions do not pose significant risks to the car and can even bring certain benefits.

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If a car with a naturally aspirated engine, usually running on AI-92, is filled with fuel with a higher octane number, for example AI-95, this will not only not harm the engine, but can also lead to improved performance. For example, fuel consumption is reduced (albeit slightly), the response to the gas pedal and acceleration dynamics are improved. These effects are associated with the presence of additives in AI-95 gasoline, which increase the engine efficiency, albeit only by 1-2%.

In addition, filling with fuel with a higher octane number helps clean the engine from carbon deposits, especially if the engine is allowed to run at high speeds. However, for modern turbocharged engines that require at least AI-95, using AI-92 is impractical due to a different degree of fuel compression incorporated into the engine design.

If there is no AI-95 at the gas station, you can not be afraid of overpaying and fill up with more expensive gasoline with an even higher octane number, for example AI-98, if it is available. It is only important to remember the quality of the fuel and fill up at trusted gas stations to avoid problems with the fuel system.

Clarifications

Petrol — a flammable mixture of light hydrocarbons with a boiling point from +33 to +205 °C (depending on impurities). Density is about 0.71…0.76 g/cm³. Calorific value is about 10,600 kcal/kg (44.4 MJ/kg, 32.7 MJ/liter). Freezing point is about −60 °C if special additives are used. Gasolines are used as motor fuel and raw material in industrial organic synthesis.

Octane number — an indicator that characterizes the detonation resistance (resistance to explosion) of fuel used in internal combustion engines with external mixture formation (usually gasoline, not used to characterize diesel fuel and aviation kerosene). The octane number is determined on a standard single-cylinder engine with a variable compression ratio. Gasoline with a higher octane number can withstand a higher compression ratio in the engine cylinders without premature self-ignition (engine knocking, “detonation”) and therefore can be used in engines with greater specific power and efficiency.

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