Should the 2020 Buick Regal use 92 or 95 octane fuel?

[VonMartin]

For the 2020 Buick Regal, the 1.5T model is recommended to use 92 octane gasoline, while the 2.0T model should use 95 octane gasoline. These fuel grades are officially recommended in the vehicle's user manual. In addition to checking the appropriate gasoline grade in the user manual, the 2020 Buick Regal also indicates the recommended fuel grade on the fuel filler cap. Typically, the fuel 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. If the compression ratio is even higher, 98 octane gasoline is recommended. However, with the application of new technologies, the compression ratio alone cannot determine the appropriate fuel grade, as high compression ratios can also be tuned to use lower octane fuel. 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 octane gasoline contains 92% isooctane and 8% n-heptane, while 95 octane gasoline contains 95% isooctane and 5% n-heptane. If the 2020 Buick Regal 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 can have the following effects: For vehicles that require low-octane fuel, using a higher octane fuel will not cause damage, but the increased octane number can 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 that require high-octane fuel, using a lower octane fuel can cause engine knocking. Because the octane number is significantly lower, the fuel's ignition point decreases, causing premature ignition during the compression stroke. If the fuel ignites before the spark plug fires, resistance occurs during the upward stroke. This resistance makes the engine run very unstably. If the knocking is mild, it may only increase noise without obvious damage to the engine. However, if the knocking is severe, it indicates serious engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring.