Should the Volvo S60 use 92 or 95 octane gasoline?

[PatrickAnn]

According to the official vehicle manual recommendation, the Volvo S60 model should use 95 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, the Volvo S60 can also refer to the fuel cap, which will also indicate the recommended octane. Generally, the fuel 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 new technologies, the compression ratio alone cannot determine the required gasoline grade, as high compression ratios can also be tuned to use lower octane fuel. This is because factors other than compression ratio, such as ignition timing, turbocharging technology, and Atkinson cycle technology, also play a role. Generally, 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 the Volvo S60 occasionally uses the wrong gasoline grade, simply switch back to the correct octane after consumption. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles recommended for lower octane, using higher octane gasoline will not cause damage, but the increase in octane value can 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 for higher octane, using lower octane gasoline can cause engine knocking. Due to the significantly lower octane value, the gasoline's ignition point decreases, causing premature ignition during the compression stroke. If the fuel ignites before the spark plug fires, resistance will occur 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.