Can I mix half 92 and half 98?
2 Answers
92 and 98 cannot be mixed. If you accidentally use the wrong gasoline grade occasionally, simply switch back to the correct grade after using it up. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles designed for lower-grade gasoline, using higher-grade gasoline will not cause damage, but the increase in octane rating will alter the fuel's ignition point, leading to delayed combustion in the engine. This means both the engine's power output and thermal efficiency will decrease, resulting in poorer performance in practice. For vehicles designed for higher-grade gasoline, using lower-grade gasoline can cause engine knocking. Because the octane rating is too low, the reduced ignition point may cause premature ignition during the compression stroke. If combustion occurs before the spark plug fires during the compression stroke, resistance will arise during the upward stroke. This resistance makes the engine run very unstably. If the knocking is mild, it may only increase noise without significant damage to the engine. However, noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring. In addition to checking the recommended gasoline grade in the vehicle's manual, you can also find it on the fuel tank cap. Generally, the gasoline grade can also be determined based on the engine's compression ratio. Vehicles with a compression ratio between 8.6-9.9 should use 92-grade gasoline, while those with a compression ratio between 10.0-11.5 should use 95-grade gasoline. However, with the use of new technologies, the compression ratio alone cannot determine the appropriate gasoline grade. High-compression engines can also be tuned to use lower-grade gasoline because factors such as ignition timing, turbocharging technology, and Atkinson cycle technology also play a role. Generally, the higher the gasoline grade, the higher the octane rating and the better the anti-knock performance. 92-grade gasoline contains 92% isooctane and 8% n-heptane, while 95-grade gasoline contains 95% isooctane and 5% n-heptane.
From my experience, mixing half 92-octane gasoline with half 98-octane is actually feasible, as long as your car engine isn't the particularly sensitive type. 92-octane has a lower octane rating, suitable for regular engines, while 98-octane with higher octane is more suited for high-performance cars. The mixed octane rating would be around 95, which is generally fine for most daily driving vehicles, but note that it's not the standard fuel recommendation. If you do this long-term, it might cause slight engine knocking or incomplete combustion, affecting fuel efficiency. Especially under high load conditions like climbing hills or highway driving, you might feel the car's acceleration isn't as smooth. Occasionally mixing once is fine, but make sure the mixture is uniform without layering. I would recommend sticking to the gasoline grade specified in your car's manual to avoid unnecessary risks, as gasoline directly relates to engine lifespan. Saving money is secondary; safety comes first.
