According to the official vehicle user manual recommendation, Beijing Hyundai models should use 92 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle user manual, Beijing Hyundai owners can also find this information on the fuel tank cap, which will be clearly marked. Generally, 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 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, the compression ratio alone cannot determine the appropriate gasoline grade. High compression ratio engines can also be tuned to use lower octane 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 speaking, the higher the gasoline octane number, the higher the octane value 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 a Beijing Hyundai 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 octane gasoline, using higher octane gasoline will not cause damage, but the increase in octane value 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 actual driving experience. For vehicles recommended to use higher octane gasoline, using lower octane gasoline can cause engine knocking. Because the octane value is too low, the gasoline's ignition point decreases and it may ignite prematurely during the compression stroke. If combustion occurs before the spark plug ignites during the compression stroke, resistance will appear in the upward stroke. This resistance can make the engine run very unstably. If the knocking is imperceptible, it only increases noise and does not cause obvious damage to the engine. However, if noticeable knocking occurs, it indicates severe engine operating conditions. The vibration not only affects driving stability but can also cause abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring.
