Does Using 95 Octane Gasoline in a Car Designed for 92 Octane Have Any Impact?
2 Answers
Using 95 octane gasoline in a car designed for 92 octane occasionally is acceptable, but long-term mixing is not recommended. When low-compression ratio engines use higher-octane gasoline, engine knocking will not occur because the lower compression ratio meets gasoline with better anti-knock properties. However, this does not mean there are no drawbacks. Since the cylinder pressure does not reach a certain level, the higher-octane gasoline is not sufficiently compressed to reach the ignition point, resulting in incomplete combustion. This prevents the engine from fully utilizing its power, wastes fuel, and can easily lead to carbon buildup in the engine. The type of gasoline a car should use is determined by its compression ratio. Generally, engines with a compression ratio between 7.5 and 8.0 should use 90–93 octane gasoline; those between 8.0 and 8.5 should use 90–93 octane; those between 8.5 and 9.0 should use 93–95 octane; and those between 9.5 and 10.0 should use 95–97 octane. The issue with using higher-octane gasoline in a low-compression ratio engine is that while it prevents knocking due to the better anti-knock properties of the fuel, it does not come without drawbacks. Since the cylinder pressure is insufficient, the higher-octane gasoline does not reach the necessary compression for optimal ignition, leading to incomplete combustion. This not only fails to maximize engine performance but also wastes fuel and increases the risk of carbon deposits in the engine.
As a veteran driver with 20 years of experience, I've refueled with both 92 and 95 octane gasoline many times. 92 octane fuel has a lower octane rating, which corresponds to regular engines with lower compression ratios, and the manual recommends using 92 octane. If you occasionally use 95 octane, the engine won't be damaged immediately. On the contrary, due to its higher octane rating, it can resist knocking, making the engine feel smoother and the combustion cleaner. However, this is only suitable for occasional experimentation. Using it long-term is simply a waste of money because the engine doesn't utilize those advanced features, and the fuel is significantly more expensive. Relatedly, I've seen some novice car enthusiasts randomly choose higher-octane fuel, thinking it will save fuel or boost performance, but the effect is minimal. The most important thing is still to maintain the vehicle regularly and not worry about minor details.
