Should the Buick Business Sedan Use 92 or 95 Octane Gasoline?

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According to the official vehicle manual recommendation, the Buick Business Sedan should use 95 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, the Buick Business Sedan can also refer to the fuel cap, which will indicate the recommended octane. Typically, 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. However, with the application of new technologies, the compression ratio alone cannot determine the required gasoline grade. High compression ratio 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. If the Buick Business Sedan occasionally uses the wrong gasoline grade, simply switch back to the correct grade after the current tank is used up. However, long-term use of the wrong gasoline grade may have the following effects: For vehicles recommended to use lower octane gasoline, using higher octane gasoline will not cause damage. However, the increase in 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 recommended to use higher octane gasoline, using lower octane gasoline may cause engine knocking. Due to the significantly lower octane number, the fuel may ignite prematurely during the compression stroke before the spark plug fires. This premature ignition creates resistance during the upward stroke, causing unstable engine operation. Mild knocking may only increase noise without significant engine damage, but severe knocking indicates serious engine issues, affecting driving stability and causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in extreme cases.