Is it better to use 92 or 95 octane fuel for Golf 6?

[DiAlexa]

According to the official vehicle manual recommendation, Golf 6 should use 95 octane fuel. In addition to checking the suitable fuel grade in the vehicle manual for Golf 6, you can also find it on the fuel tank cap, which will be clearly marked. 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 fuel, while those with a compression ratio between 10.0-11.5 should use 95 octane fuel. However, with the application of some new technologies nowadays, the fuel grade cannot be solely determined by the compression ratio. A high compression ratio can also be adjusted to use lower octane fuel. 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 fuel grade, the higher the octane number and the better the anti-knock performance. 92 octane fuel contains 92% isooctane and 8% n-heptane, while 95 octane fuel contains 95% isooctane and 5% n-heptane. If Golf 6 occasionally uses the wrong fuel grade, simply switch back to the correct fuel grade after using it up. However, long-term use of the wrong fuel grade may have the following effects: For vehicles recommended to use lower octane fuel, using higher octane fuel by mistake will not cause damage. However, 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 actual driving experience. For vehicles recommended to use higher octane fuel, using lower octane fuel may cause engine knocking. Due to the significantly lower octane number, the fuel's ignition point decreases and may ignite prematurely during the compression stroke. If the fuel ignites before the spark plug fires during the compression stroke, resistance will occur during the upward stroke. This resistance will make the engine run very unstably. If it's mild knocking, it only increases noise without obvious damage to the engine. However, if there is noticeable knocking, it indicates severe engine conditions. The vibration not only affects driving stability but also causes abnormal wear on pistons and cylinders, and in severe cases, may lead to cylinder scoring.