Should the Regal 1.5T use 92 or 95 gasoline?

[VanCarlos]

According to the official vehicle manual recommendation, the Regal 1.5T should use 92 gasoline. In addition to checking the suitable gasoline grade in the vehicle manual, the Regal 1.5T can also refer to the label on the fuel tank cap. Typically, the appropriate 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 compression ratio alone cannot determine the gasoline grade. High compression ratio engines can also be tuned to use lower-grade gasoline due to other influencing factors such as ignition timing, turbocharging technology, and Atkinson cycle technology. 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 Regal 1.5T 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, using higher-grade gasoline 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 results in reduced engine power and thermal efficiency, with the practical feedback being 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 gasoline's ignition point decreases, causing 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. If the knocking is imperceptible, it only increases noise without obvious damage to the engine. 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.