Can a car that uses 92 octane fuel be filled with 95 octane?
2 Answers
It is acceptable to occasionally fill a car that normally uses 92 octane with 95 octane fuel. Using higher octane fuel in a vehicle designed for lower octane has no negative effects, though it may waste some of the fuel's performance potential. However, a car designed for high octane fuel should not use lower octane fuel, as this can cause engine knocking. Meaning of gasoline octane ratings: The octane rating represents the ratio of the actual gasoline's anti-knock properties compared to standard reference fuels. Higher octane numbers indicate stronger anti-knock performance. Gasoline composition: Standard reference fuels consist of isooctane and n-heptane. Higher octane numbers aren't necessarily better - the appropriate octane rating should be selected based on the engine's compression ratio. Isooctane has good anti-knock properties with an octane rating of 100, while n-heptane has poor anti-knock properties and is prone to knocking in gasoline engines, with an octane rating of 0. If gasoline is labeled as 90 octane, it means this gasoline has the same anti-knock properties as a standard reference fuel containing 90% isooctane and 10% n-heptane.
I used to drive many cars that ran on 92-octane gasoline. Once, when the gas station only had 95-octane fuel left, I decided to try it. As a result, the engine noise became slightly quieter, acceleration felt smoother, and there were no issues at all. Later, I asked a friend at the repair shop, and he explained that higher-octane fuel has better anti-knock properties, which offers better engine protection without causing harm. However, using it long-term might be a waste of money since 95-octane is more expensive, and if the car is designed for 92-octane, the performance improvement is minimal. He suggested that occasionally using 95-octane is fine, but it's best to follow the owner's manual and avoid using lower-octane fuel, as that could cause knocking and damage the engine. Overall, safety comes first—if you encounter special circumstances, temporarily using 95-octane is acceptable.
