Is it better to use 92 or 95 octane gasoline for Santana?

[KylieMarie]

According to the official vehicle manual recommendation, Santana should use 92 octane gasoline. In addition to checking the suitable gasoline grade in the vehicle manual, Santana owners can also find this information on the fuel tank cap, which will be clearly marked. Generally, 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 octane gasoline, while those with a compression ratio between 10.0-11.5 should use 95 octane gasoline. However, with the application of some new technologies nowadays, the compression ratio alone cannot determine the gasoline grade to use. Even engines with high compression ratios can be tuned to use lower-grade gasoline. This is because, apart from the compression ratio, 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 Santana 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 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 means both the engine's power output and thermal efficiency will decrease, resulting in poorer performance in practice. For vehicles recommended to use higher-grade gasoline, using lower-grade gasoline can cause engine knocking. Because the octane number is significantly lower, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If combustion occurs before the spark plug ignites during the compression stroke, resistance will arise during the upward stroke. This resistance will make the engine run very unstably. If the knocking is imperceptible, it will only increase noise without obvious damage to the engine. However, if the knocking is noticeable, it indicates severe engine conditions. The vibration not only affects driving stability but can also cause abnormal wear on the pistons and cylinders, and in severe cases, even cylinder scoring.