Should the Passat Lingyu use 92 or 95 octane gasoline?
2 Answers
According to the official car manual recommendation, the Passat Lingyu should use 92 octane gasoline. In addition to checking the suitable gasoline grade in the car manual, the Passat Lingyu can also check the fuel tank cap, which will also indicate the appropriate gasoline grade. Usually, the gasoline grade can also be determined based on the engine's compression ratio. Cars with an engine compression ratio between 8.6-9.9 should choose 92 octane gasoline, while those with a compression ratio between 10.0-11.5 should choose 95 octane gasoline. However, with the use of some new technologies, the gasoline grade cannot be solely determined by the compression ratio. A high compression ratio can also be adjusted to use low-grade gasoline because, in addition to 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 the Passat Lingyu occasionally uses the wrong gasoline grade, simply switch back to the correct gasoline grade after use. However, long-term use of the wrong gasoline grade may have the following effects: For vehicles recommended to use low-grade gasoline, using high-grade gasoline by mistake will not cause damage, but the increase in octane number will change the fuel's ignition point, leading to delayed combustion in the engine. This means the engine's power output and thermal efficiency will decrease, and the actual feedback experience is reduced power. For vehicles recommended to use high-grade gasoline, using low-grade gasoline may cause engine knocking. Because the octane number is too low, the gasoline'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 cause the engine to run very unstably. If it is only slight knocking, the noise will increase, but the damage to the engine is not obvious. If there is obvious knocking, it indicates that the engine's working condition is already very severe. The vibration not only affects driving stability but also causes abnormal wear on the piston and cylinder, and in severe cases, may even lead to cylinder scoring.
I've been driving my Passat Lingyu for almost three years now, and I've only used 95-octane fuel because the manual recommends that this car's high-compression ratio engine requires high-octane fuel to prevent knocking. While 92-octane fuel is cheaper, it's risky. Once, a friend borrowed my car and filled it with 92-octane, and the engine shook badly with poor acceleration—costing me a lot in repairs. Since then, I never take the risk. Although 95-octane is slightly more expensive, the ride is smoother, fuel efficiency is better, and the actual cost difference isn’t significant. With the right fuel, the car responds quickly, giving me confidence when overtaking on highways and peace of mind on long trips. Remember, gas stations sometimes push cheaper fuel—always check the octane rating to avoid being tricked. Also, during maintenance, pay attention to spark plug carbon buildup and inspect it regularly. This habit has kept my car out of the repair shop, saving me money and hassle.
