Can I Add 95 Octane Gasoline Before the 92 Octane is Completely Used Up?
3 Answers
It is not recommended to add 95 octane gasoline before the 92 octane is completely used up. Gasoline is a mixture, and the octane rating we usually refer to indicates the fuel's different anti-knock indexes. Short-term use will not cause significant damage to the engine because the anti-knock performance of gasoline itself is improving. The chemical compositions of the two gasoline types are relatively similar, but they contain different additives. Prolonged mixing can affect ignition timing, leading to higher fuel consumption and lower power output. The octane rating is an indicator of anti-knock performance and is essentially unrelated to cleanliness, power, or combustion value. The higher the octane rating, the stronger the fuel's ability to resist engine knocking. The main difference between 92 octane and 95 octane gasoline is that 95 octane has a stronger anti-knock capability than 92 octane.
I'm an ordinary office worker driving an economy sedan for daily commuting. There's no problem mixing 95-octane gasoline when 92-octane isn't fully consumed - I've done this before without noticing any abnormal performance. The engine runs smoothly with normal fuel consumption. The mixed fuel's octane rating averages between the two, potentially slightly improving combustion efficiency and reducing knock risk. However, long-term mixed fueling might affect engine adaptation, especially causing issues like vibration or increased carbon deposits in older vehicles. Many people occasionally do this for cost savings and convenience - it's generally fine for non-performance vehicles. I suggest not making it a habit; it's better to wait until the tank is nearly empty before refueling with a new grade to avoid engine stress. Modern car designs have high tolerance for mixed fuels, but frequently switching grades isn't ideal - playing it safe is more worry-free.
I have been engaged in car maintenance for many years and often encounter customers mixing fuel. It is feasible to add 95-octane gasoline when 92-octane is not completely burned out. The engine can generally adapt to mixed gasoline, and the octane rating between 92 and 95 may make combustion smoother. However, it is important to note the differences in vehicle models. For example, mixing fuel in high-compression engines may reduce performance or increase the likelihood of knocking. After mixing, it is recommended to drive for a while to observe the engine sound and fuel consumption. If everything is normal, there is no issue. If the fuel quality is impure or contains many impurities, it may clog the fuel lines. For safety reasons, it is best to follow the recommended fuel grade in the owner's manual, and mixing should only be done in emergencies. Long-term mixing, while not fatal, may slightly affect the lifespan of spark plugs or the catalytic system. Timely cleaning of the fuel tank or checking the fuel filter can prevent problems.
