Can Shell and PetroChina Gasoline Be Mixed?
2 Answers
Shell and PetroChina gasoline can be mixed as long as they have the same octane rating. Gasolines with different formulations share the same base oil, differing only in additives. However, these additives do not affect gasoline usage—only the octane rating impacts engine performance. Therefore, gasolines from different stations can be mixed if they share the same octane rating. The octane rating represents the ratio of the actual gasoline's anti-knock properties to those of standard gasoline. A higher octane rating indicates stronger anti-knock performance. Standard gasoline consists of isooctane and n-heptane, and a higher octane rating is not necessarily better. The appropriate octane rating should be chosen based on the engine's compression ratio.
As an ordinary person who has been driving a family car for over ten years, I usually just go for the cheapest gas available. Sometimes mixing Shell and PetroChina fuels does work fine, and the engine runs quite smoothly. The main reason is that gasoline standards are pretty similar nowadays, like the current China VI fuel standard, which strictly controls impurities, so mixing them won’t damage the engine. However, the additive formulations might differ—Shell focuses more on new-tech additives to clean the fuel system, while PetroChina’s fuel is more budget-friendly. Long-term mixing might occasionally cause slight fluctuations in fuel consumption or minor changes in engine sound, but for short city drives, it’s no big deal. I’d recommend minimizing mixing since mismatched additives could affect the fuel system’s lifespan. When refueling, try to stick to one brand for a full tank—saving money should still consider safety. If you notice abnormal engine vibrations, just get it checked promptly. For regular commutes, there’s really not much to worry about.
