Changan Oushang X5: Should You Use 92 or 95 Octane Gasoline?

[DelLyla]

According to the official vehicle manual recommendation, the Changan Oushang X5 should use 92 octane gasoline. In addition to checking the suitable gasoline grade in the vehicle manual, you can also find it marked on the fuel tank cap of the Changan Oushang X5. 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 octane gasoline, while those with a compression ratio between 10.0-11.5 should opt for 95 octane gasoline. However, with the application of some new technologies, the compression ratio alone cannot determine the gasoline grade, as engines with high compression ratios can also be tuned to use lower-grade gasoline. This is because, besides 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 you occasionally use the wrong gasoline grade in the Changan Oushang X5, 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 may alter the fuel's ignition point, leading to delayed combustion in the engine. This results in reduced engine power and thermal efficiency, with the actual 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 fuel'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.