Can a Car Designed for 92 Octane Use 95 Octane Fuel?

[ZacharyMarie]

A car designed for 92 octane gasoline can use 95 octane fuel, but it is not recommended for long-term use. Prolonged mixing of different octane ratings will affect the service life of the car's ignition system, fuel injectors, and spark plugs, leading to earlier major repairs. The appropriate octane rating can be determined based on the engine's compression ratio. Cars with a compression ratio between 8.6-9.9 should use 92 octane gasoline, while those with a compression ratio between 10.0-11.5 should use 95 octane gasoline. For higher compression ratios, 98 octane gasoline is recommended. However, with the use of new technologies, the octane rating cannot be solely determined by the compression ratio. High compression ratio engines can also be tuned to use lower octane fuel due to other influencing factors such as ignition timing, turbocharging technology, and Atkinson cycle technology. Generally, the higher the octane rating, the higher the octane number and the better the anti-knock performance. 92 octane gasoline contains 92% isooctane and 8% n-heptane, while 95 octane gasoline contains 95% isooctane and 5% n-heptane. Occasionally using the wrong octane rating only requires switching back to the correct one after use. However, long-term use of the wrong octane rating can have the following effects: For vehicles designed for lower octane fuel, using higher octane fuel will not cause damage, but the increase in octane number will change the fuel's ignition point, leading to delayed combustion in the engine. This reduces the engine's power output and thermal efficiency, resulting in poorer performance. For vehicles designed for higher octane fuel, using lower octane fuel can cause engine knocking. The significantly lower octane number reduces the fuel's ignition point, causing premature ignition during the compression stroke. If combustion occurs before the spark plug ignites, resistance will occur during the upward stroke. This resistance makes the engine run very unstably. Mild knocking only increases noise without significant engine damage, but severe knocking indicates serious engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring. Considerations when choosing gasoline: Select gasoline with appropriate volatility based on the car's operating temperature. Gasoline with good volatility ensures easy cold starts and balanced engine warm-up. However, excessive volatility can easily cause vapor lock in the fuel lines, preventing the fuel pump from functioning properly and leading to engine stalling. Choose gasoline based on its lead content.