What indicators are used to classify gasoline grades?

[EmersynDella]

Automotive gasoline grades are classified by Motor Octane Number (MON) into five grades: 66, 70, 75, 80, and 85. The numerical grade indicates the octane number measured by the Motor method, with grades 75, 80, and 85 suitable for high-end vehicles. The GB489—86 "Gasoline Specifications" stipulate three grades: 66, 70, and 85, with the numerical grades representing the octane number measured by the Motor method. More details are as follows: 1. Grade issuance time: The new standard GB484—89 issued in 1989 stipulates that automotive gasoline grades are classified by Research Octane Number (RON) into three grades: 90, 93, and 97. The numerical grades indicate the octane number measured by the Research method. For the same gasoline, the octane number measured by the Research method is 8~10 units higher than that measured by the Motor method, with Motor Octane Number = Research Octane Number × 0.8 + 10. 2. Meaning of gasoline grades: Simply put, gasoline grades represent the anti-knock coefficient, or octane number. The so-called 90, 93, and 97 unleaded gasoline grades indicate that they contain 90%, 93%, and 97% of the highly anti-knock "iso-octane," respectively, meaning they contain 10%, 7%, and 3% of the poorly anti-knock n-heptane, respectively.

[SophiaLynn]

Gasoline grades are classified by octane rating, which indicates the fuel's resistance to knocking. Knocking refers to that annoying pinging sound in the engine, which harms the engine and is quite bothersome. The higher the octane rating, the less likely the gasoline is to auto-ignite under high pressure. Therefore, higher-grade fuels like 91 octane have better anti-knock properties and are suitable for high-compression engines such as sports cars. The higher the compression ratio, the more sensitive the engine becomes, making it prone to issues with lower-grade gasoline. Having driven for many years, I've seen many people carelessly use lower-grade fuel, resulting in engine vibration, reduced power, and in severe cases, potential piston damage. Actually, octane ratings are globally standardized—for example, US 87 octane is roughly equivalent to China's 92 octane. The key when choosing fuel is to follow the vehicle manual's recommendation rather than guessing blindly, otherwise your car might throw a tantrum.

[DiLeah]

From a practical driving perspective, gasoline grades are determined by octane ratings, which essentially indicate anti-knock capability. Higher-grade gasoline allows the engine to run more smoothly, as modern vehicles increasingly feature higher compression ratios—turbocharged engines, for example, require high-grade fuel to prevent knocking. Knocking not only reduces power output but also increases fuel consumption and emits harmful substances. I recall trying lower-grade fuel for city driving, and during hard acceleration, the engine exhibited minor vibrations, akin to indigestion. The key lies in matching the engine design: economy cars perform adequately with 87 or 92 octane, while sports cars demand 95 or 98. Standards vary slightly worldwide—Europe uses RON values, whereas the U.S. employs the average of octane ratings. Always adhere to the grade recommended in your vehicle’s manual; saving pennies here risks costly damage.

[Barros]

Many people mistakenly believe that higher-grade gasoline is cleaner or more fuel-efficient, but the truth is that the grade is classified by octane rating, specifically designed to resist knocking. Knocking is the enemy of high-compression engines, reducing efficiency and damaging components. Grades like 87 and 95 represent octane levels: the higher the number, the more stable the fuel is in the combustion chamber. A simple test is to listen for abnormal noises when the engine is climbing hills. Don’t be fooled into thinking higher-grade gasoline boosts performance—it only prevents knocking, not increasing power. Basic cars can run perfectly fine on lower-grade fuel; upgrading unnecessarily is a waste of money. Octane ratings are measured in labs and are consistent worldwide, with the core goal of protecting the engine and ensuring safe driving.

[Carvalho]

Choosing the right gasoline grade during refueling is crucial, as it's based on the octane rating standard: the higher the value, the better the anti-knock performance. Engine knocking can shorten engine life, so it's essential to match the gasoline grade with the car's compression ratio. For example, older cars with low compression ratios can use 87 octane, while newer, high-efficiency engines require 92 or 95 octane or higher. I recommend car owners not to experiment randomly but to first check the recommended grade in the vehicle manual. Using the wrong gasoline not only wastes money but can also lead to carbon buildup, affecting acceleration response. In fact, the grading system varies globally: for instance, 89 octane regular gasoline in the U.S. corresponds to 92 octane in China. Additionally, don't be misled by advertisements; the octane rating only affects knocking resistance and has no bearing on fuel quality. Regularly check the fuel quality during maintenance to ensure the engine runs healthily.

[StKyle]

The concept of gasoline grades dates back to the 1920s, categorized by octane ratings: higher values indicate stronger anti-knock performance, such as 89-octane fuel with an octane value around 87-89. Octane rating measurement involves laboratory simulations of compression conditions—higher values mean the fuel is more stable under high pressure, preventing auto-ignition. The rise in engine compression ratios drove the need for grade differentiation; older cars with low compression ratios used lower grades, while modern cars with ratios above 10:1 require higher grades. Global systems vary slightly, with Europe using RON values and the U.S. combining RON and MON for determination. The core principle is engine protection: lower grades risk knocking, while higher grades offer smoother performance but at a higher cost. Always follow the manufacturer's guidelines when selecting fuel to avoid damage.