Can I Add 92 Octane Gasoline When Half a Tank of 95 Octane Remains?
2 Answers
It is possible to add 92 octane gasoline when half a tank of 95 octane remains, which constitutes gasoline mixing. Occasional mixing will not affect the vehicle, but it is not recommended to do so frequently as it may burden the engine operation, increase wear, and lead to issues such as knocking and insufficient power. Long-term mixing of different octane grades will affect the service life of the car's ignition system, fuel injectors, and spark plugs, advancing the time for major vehicle repairs. Hazards of long-term mixing of 95 octane and 92 octane gasoline: Strictly speaking, 92 octane and 95 octane gasoline should not be mixed. However, their chemical compositions and other aspects are relatively similar, with strong anti-knock properties. Generally, mixing them does not cause significant problems. After short-term mixing of different octane grades, special maintenance for the vehicle is usually not required. However, it is recommended that car owners strictly adhere to the vehicle's requirements for the corresponding octane grade when conditions permit. For instance, adding 95 octane gasoline to a car that originally uses 92 octane generally does not cause issues, but the reverse may lead to vehicle damage. Using lower octane gasoline may cause engine knocking, and in severe cases, may result in bent valves or damage to the valve cover. Differences between 92 octane and 95 octane gasoline: 92 octane gasoline has an octane rating of 92 and is suitable for mid-range cars (with relatively low compression ratios). On December 18, 2013, the General Administration of Quality Supervision, Inspection and Quarantine and the National Standardization Management Committee jointly issued the fifth-stage national standard for automotive gasoline—"Automotive Gasoline". 95 octane gasoline is automotive gasoline with a research octane number not less than 95 and an anti-knock index not less than 90.
Mixing 95 and 92 octane gasoline starts with understanding engine construction. 95 octane has higher anti-knock properties, suitable for high-compression engines to prevent knocking. If you mix 92 octane into a half-tank of 95, the overall octane rating drops, potentially causing engine knocking or unstable performance. Modern cars with ECU can adjust ignition timing, but it's less reliable than using the recommended fuel. I once mixed them in an emergency and noticed sluggish acceleration - definitely not recommended long-term as it harms the engine. Always follow the manual; don't sacrifice engine longevity for convenience. After this mixed tank, refill with pure 95 octane as soon as possible.
