Can Turbocharged Engines Use 92 Octane Gasoline?

[DelLilliana]

Some turbocharged models can use 92 octane gasoline, but it is recommended to follow the official vehicle owner's manual. In addition to checking the suitable gasoline grade in the owner's manual, you can also find this information on the fuel tank cap. The fuel tank cap will usually indicate the recommended octane rating. Generally, the gasoline grade can also be determined based on the engine's compression ratio. Vehicles with an engine 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 compression ratio alone cannot determine the appropriate gasoline grade. High-compression engines can also be tuned to use lower-octane gasoline due to other influencing factors such as ignition timing, turbocharging technology, and Atkinson cycle technology. Generally, the higher the gasoline 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 gasoline grade is not a problem—simply switch back to the correct grade after the tank is empty. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles designed for low-octane gasoline, using a higher octane rating will not cause damage, but the increased octane number may alter 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 high-octane gasoline, using a lower octane rating can cause engine knocking. Since the octane number is significantly lower, the gasoline's ignition point decreases, causing premature ignition during the compression stroke. If combustion occurs before the spark plug fires, resistance will develop during the upward stroke. This resistance makes the engine run very unevenly. If the knocking is mild, it may only increase noise without obvious engine damage. However, noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring.