What do gasoline grades 95, 92, and 98 mean?

[BethanyDella]

Gasoline grades 92, 95, and 98 represent different levels of isooctane content in the fuel, while the fuel quality and the heat value per unit volume remain the same. Octane Rating: The numbers indicate the octane rating of the gasoline. The higher the number, the higher the octane rating, which means the gasoline has better anti-knock properties. For example, 92-grade gasoline contains 92% octane, 95-grade contains 95%, and 98-grade contains 98%. Anti-Knock Properties: When the air-fuel mixture is injected into the cylinder, the piston compresses the mixture, increasing pressure and temperature. If the gasoline's anti-knock properties are too low, the mixture may ignite before the spark plug fires, leading to uncontrolled combustion, commonly known as knocking. Higher octane ratings provide better anti-knock properties, reducing potential engine damage.

[LaJeremiah]

I have a good understanding of car engines. The numbers like 92, 95, and 98 on gasoline represent the octane rating, which simply indicates the fuel's resistance to knocking. For example, 98-octane gasoline has the highest resistance to knocking and is suitable for high-compression engines, such as those in sports cars or turbocharged vehicles, because they operate under intense conditions where regular gasoline might ignite prematurely in the cylinders. 92-octane is cheaper and perfectly fine for regular family cars in daily driving. Some car enthusiasts think using higher-octane fuel saves more gas, but it's unnecessary—just stick to the recommended grade for your car model. If you use the wrong gasoline, like filling up with 92 when 95 is required, the engine might produce a knocking sound, and in severe cases, it could damage the pistons, leading to serious trouble.

[StSophie]

I often think about fuel grades when driving. The numbers 92, 95, and 98 mainly indicate different anti-knock performances. The higher the number, the better it can withstand high pressure. For example, 98-octane fuel is less prone to self-ignition under high temperature and pressure in the engine, avoiding premature ignition and knocking. For regular family cars with low compression ratios, 92-octane is sufficient for daily commuting. Using 95 or 98-octane would just be a waste of money. However, some people prefer 98-octane, believing it provides quicker power response, though the actual difference is minimal. I’ve personally tried mixing different grades in the same tank and didn’t notice much difference. When refueling, always check the recommended grade on the fuel cap. Never skimp by using a lower grade—damaging the engine will cost much more to repair.

[HectorFitz]

I often encounter cases of incorrect gasoline grade usage during car repairs. 92 and 98 represent the octane rating levels, with 98 being suitable for high-precision engines while older cars can use 92. The consequences of using the wrong fuel are severe: if a high-compression engine uses 92-grade gasoline, it may cause pre-ignition leading to severe knocking, and prolonged use will damage spark plugs and pistons. Repair costs can easily reach thousands, so always check the vehicle manual before refueling. Additionally, gasoline compositions vary by region, so when driving abroad, make sure to verify the local grade equivalents to avoid engine damage from misfueling.