Should the Buick GL8 use 92 or 95 gasoline?

[StAurora]

According to the official vehicle manual recommendation, the Buick GL8 should use 95 gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, the Buick GL8 can also refer to the label on the fuel tank cap. 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 gasoline, while those with a compression ratio between 10.0-11.5 should use 95 gasoline. However, with the application of new technologies, the gasoline grade cannot be solely determined by the compression ratio. A high compression ratio can still be adjusted to use lower-grade gasoline, as other factors such as ignition timing, turbocharging technology, and Atkinson cycle technology also play a role. Generally, the higher the gasoline grade, the higher the octane number and the better the anti-knock performance. 92 gasoline contains 92% isooctane and 8% n-heptane, while 95 gasoline contains 95% isooctane and 5% n-heptane. If the Buick GL8 occasionally uses the wrong gasoline grade, simply switch back to the correct grade after consumption. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-grade gasoline, accidentally using higher-grade gasoline will not cause damage, but the increase in octane number will 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-grade gasoline, using lower-grade gasoline can cause engine knocking. Due to the significantly lower octane number, the fuel's ignition point decreases, leading to premature ignition during the compression stroke. If combustion occurs before the spark plug ignites, resistance will arise during the upward stroke. This resistance makes the engine run very unstably. Mild knocking may only increase noise without significant engine damage, but noticeable knocking indicates severe engine conditions, affecting driving stability and causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in severe cases.