Can 95 and 98 gasoline be mixed?
2 Answers
98 and 95 gasoline cannot be mixed. Using lower-octane gasoline in high-octane vehicles will severely affect the normal operation of the engine, leading to knocking and, in severe cases, reducing the engine's lifespan. Methods for correctly selecting gasoline octane ratings: Choose different octane ratings based on the engine's compression ratio; each vehicle's manual will indicate the engine's compression ratio. For a compression ratio of 7.5-8.0, use 90-octane gasoline; for 8.0-8.5, use 90 or 93-octane gasoline; for 8.5-9.5, use 93 or 95-octane gasoline; for 9.5-10, use 95 or 97-octane gasoline. Choose gasoline with good stability; gas stations from major brands like Sinopec, PetroChina, and CNOOC are more reliable. Choose gasoline with low olefins, low aromatics, and low sulfur; olefins can easily form gums and carbon deposits, clogging fuel lines; aromatics increase CO emissions, causing severe pollution and affecting human health; elemental sulfur and sulfides have strong corrosive effects on metals, accelerating the scrapping of gasoline engines.
I've been driving for over 20 years and often encounter gas stations without 98-octane fuel. Mixing 95 and 98 is theoretically possible because the fuel will blend uniformly in the tank, resulting in an intermediate octane level, and the engine can generally run. However, I don't recommend doing this frequently, especially if your vehicle's manual specifies 98-octane gasoline. Why? Because engines are designed for a specific octane rating, and mixing lowers the octane, increasing the risk of knocking—also known as engine ping—which can damage cylinders and pistons over time. I once tried mixing, and the car shook violently with noticeably slower acceleration. It's best to stick to the recommended fuel grade to avoid extra repair costs. If you must mix, only do so in emergencies when fuel is scarce, and refill with the specified grade as soon as possible.
