The label actually means the anti-knock value. The so-called anti-knock is the stability of the harsh environment under high compression ratio, high temperature and high frequency. Junior high school physics may not remember the experiment of igniting matches with compressed air. This is where the knocking comes in. Under the high-speed operation of the engine piston, the same effect will be produced. If the anti-knock value is low, it is likely that the gasoline mixture has already ignited in the compression section. The ignition means that the gas needs to expand, but the piston is in the compression stroke. It will be in vain, and even lead to momentum hedging.

The role of anti-knock here is that this kind of engine, compressed to the top, the average maximum working temperature, and 6000 rpm, can ensure that it will not be compressed and ignited. This is the basic meaning of the label. We usually say No. 92, No. 95 No. 98 gasoline, this value represents the grade of gasoline, that is, the ratio of the antiknock resistance of actual gasoline to that of standard gasoline. The higher the label, the stronger the anti-knock performance. Standard gasoline is composed of isooctane and n-heptane. Isooctane has good antiknock performance, and its octane number is set at 100; n-heptane has poor antiknock performance and is prone to knocking on gasoline engines, and its octane number is set at 0.

If the gasoline label is 92, it means that the gasoline of this label has the same anti-knock performance as the standard gasoline containing 92% isooctane and 8% n-heptane. The only criterion for choosing gasoline label is the compression ratio of the motorcycle engine. Generally speaking, the higher the compression ratio of the engine, the smaller the compressed volume of the combustible mixture, the more powerful the engine, and the lower the fuel consumption. However, the compression ratio must be matched with another index, which is the antiknock index of gasoline, also known as octane number, that is, gasoline label. The higher the compression ratio of the engine, the higher the anti-knock index of gasoline is required, that is, the higher the gasoline's label. China's automobile and motorcycle engines are mainly imported or produced with reference to foreign standards. At present, there are only three types of gasoline in the foreign oil market: 92, 95, and 98. The compression ratio of the engine is also designed with reference to these three types. There are not many engines that match gasoline.

However, the phenomenon of lowering the standard oil is very common now. According to calculation and observation, the compression ratio of small cars is mostly above 9.0, and the compression ratio of some imported cars is even above 10.8. These should use gasoline of No. 95 or above.

Common saying: Generally speaking, the larger the compression ratio, the higher the gasoline grade. Usually, the compression ratio of 8.0-9.5 should use No. 92-95 motor gasoline; the compression ratio above 9.5 should use No. 95-98 gasoline.