Gasoline for American cars – what is the best way to fill them?

To be honest, there are real reasons to consider American engines low-powered, omnivorous gas guzzlers, and more than one. But, firstly, it was a long time ago, and, secondly, in many ways it was not true. And even more so today.

What do Americans need?

One of the reasons why American cars are believed to be “powered” by low-octane fuel is the stickers near the fuel tank containing the numbers 91, 89 and 87. At the same period, this is not exactly what our A-80 means, A-92, AI-93, A-95.

Although the indicated numbers in both cases are the octane number of gasoline, they are obtained using different methods. So, for a direct comparison you need to know which way they all got.

Research method. It affects both RON (from the English Research Octane Number) and is common in most European countries. Therefore, all European gasolines are tested for octane number using the test method.

Motor mode . It is indicated in the documents by the letters MON (Motor Octane Number) and is used to evaluate the properties of fuel on the American continent.

There are several less common methods: RdON (Road Octane Number) and PON (Pump Octane Number), also used in America.

Without using the exact method of checking the level of the engine, we will tell about the main thing: each method named in more detail indicates the behavior of the fuel under the operating conditions of the engine “a”. For example, the motor method shows the quality of the fuel under heavy loads, such as high speed, climbing, acceleration with the throttle partially open. In addition, the octane number according to the analysis method provides the characteristics of gasoline when the engine works in mobile modes, that is, when the load changes.

Octane Rating in America

In order to obtain fuel with the most universal properties, American engineers created their own ultimate indicator of gasoline anti-knock stability: AKI (Anti-Knock Index – anti-knock index). It is still based on common methods, but is defined as the arithmetic mean between the OR for the motor method and the inspection method. The indicators obtained by different methods for the same gasoline are added together and divided by two: (MON + RON) / 2 = AKI. Let’s say that the Americans see our good old A-92 as follows: (92+83)/2=87.5. And our A-95 would have received the mark 90: (95 + 85) / 2 = 90 according to AKI.

As a result, we can see that American engines are not at all omnivorous, but rather capricious if we take their signs to the values ​​we know. Of course, this also applies to cars of European and Asian brands that were made especially for the foreign market.

Approximate composition of commercial gasolines according to European and American classifications.

Gasoline in Europe – Gasoline in America

• А-98 – 91 (Premium), 92 (Premium), 93 (Advanced)
• А-95 – 89 (More)
• А-92 – 87 (regular)

In short

For a modern injection engine, of course, full compliance with the octane number of fuel is not required, so it is more common to accept separations of 1 – 2 units. Because the electronic control unit continues to monitor the operating parameters of the engine and continuously adjusts the timing of ignition and the supply of gasoline portions to the cylinders. And if the sensors detect the most harmful thing to the engine – an explosion, it will be removed immediately.

At the same time, there are some models of high-speed engines for which refueling with A-98 gasoline is very important. On the other hand, it is not advisable to feed your engine with gasoline with a higher octane rating than the car manufacturer requires. Because the power unit designed for the A-92 will not show anything special when it works on the “ninety-five” or “ninety-eight”. It is much more important that gasoline meets the recommended environmental standard (Euro-4, Euro-5) and does not contain too much ferrocenes, sulfur, aromatics and alcohol.