Should the DL250 use 95 or 92 octane gasoline?

[GiaDella]

According to the official vehicle manual recommendation, the DL250 should use 95 octane gasoline. Using gasoline with a lower octane rating may cause engine knocking. In addition to checking the appropriate gasoline grade in the vehicle manual, the DL250's fuel cap also indicates the recommended octane rating. Generally, the required gasoline grade can also be determined by the engine's compression ratio. Vehicles with a 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 new technologies, the compression ratio alone cannot determine the required gasoline grade. Engines with high compression ratios can also be tuned to use lower octane gasoline because other factors, such as ignition timing, turbocharging technology, and Atkinson cycle technology, also play a role. Generally, the higher the gasoline octane rating, 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 DL250 occasionally uses the wrong gasoline grade, simply switch back to the correct octane rating 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 increased octane number may 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 recommended to use higher octane gasoline, using lower octane 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 fires during the compression stroke, resistance will arise during the upward stroke. This resistance makes the engine run very unstably. If the knocking is mild, it may only increase noise without significant engine damage. However, noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in severe cases.