Can I add 95 octane fuel when 92 octane is not completely used up?
2 Answers
It is possible to add 95 octane fuel when 92 octane is not completely used up, but prolonged mixing of different gasoline grades should be avoided as it may negatively impact the vehicle's performance. Issues such as engine knocking, insufficient power output, and increased engine wear may occur. More details are as follows: 1. Many car owners have experience mixing gasoline, most commonly 92 and 95 octane. Occasional mixing (once or twice) will not affect normal vehicle operation, but long-term mixing can lead to knocking and power loss. 2. Prolonged mixing of gasoline grades increases the frequency of engine knocking and accelerates engine wear. 3. If the vehicle's standard fuel requirement is 92 octane, prolonged use of 95 octane fuel may cause carbon deposits to form in the engine over time. 4. The cleanliness of gasoline is determined by national standards, not by the octane rating. The octane number represents the fuel's resistance to knocking—for example, 92 octane gasoline contains approximately 92% isooctane, while 95 octane contains about 95%. Higher-octane fuels have better anti-knock properties due to the higher isooctane content.
As someone who often does DIY car maintenance, I think it's perfectly fine to add 95 octane fuel when the 92 octane hasn't run out completely. The car's sensors are smart enough to detect the change in octane rating and automatically adjust the ignition timing. Once when my fuel gauge was nearly empty and I couldn't find 92 octane, I directly filled half a tank with 95 octane, and the engine actually ran smoother. However, I should remind you that occasional mixing is okay, but don't keep switching back and forth between 92 and 95 octane, as different additives mixing together may produce gum that could clog the fuel injectors. If you're really not confident, it's recommended to wait until the fuel level is below one quarter before changing the octane rating.
