Should the GM8 use 92 or 95 gasoline?
2 Answers
GM8 should use 92-octane gasoline, as this fuel grade is recommended in the vehicle's official user manual. In addition to checking the appropriate gasoline grade in the user manual, the GM8's fuel cap will also indicate the recommended grade. Typically, the fuel 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-octane gasoline, while those with a compression ratio between 10.0-11.5 should use 95-octane gasoline. If the compression ratio is even higher, 98-octane gasoline is recommended. However, with the application of new technologies, the compression ratio alone cannot determine the appropriate gasoline grade, as high-compression engines can also be tuned to use lower-octane fuel. Other 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 number and the better the anti-knock performance. 92-octane gasoline contains 92% isooctane and 8% n-heptane, while 95-octane gasoline contains 95% isooctane and 5% n-heptane. If the GM8 occasionally uses the wrong gasoline grade, simply switch back to the correct grade after consumption. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-octane gasoline, using a higher grade will not cause damage, but the increased octane number alters the fuel's ignition point, leading to delayed combustion in the engine. This reduces the engine's power output and thermal efficiency, resulting in poorer performance. For vehicles recommended to use higher-octane gasoline, using a lower grade can cause engine knocking. The significantly lower octane number lowers the fuel's ignition point, causing premature ignition during the compression stroke. If detonation occurs before the spark plug fires, resistance is generated during the upward stroke. This resistance makes the engine run very unstably. Mild knocking may only increase noise without obvious engine damage, but severe knocking indicates serious engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in extreme cases.
I've been driving the GAC GM8 for quite some time now, and I feel that choosing gasoline depends on the engine's tolerance. The main difference between 92 and 95 octane lies in the octane rating—higher octane means better anti-knock performance, which means it's less likely to cause knocking under high temperatures. The GM8's 2.0T engine doesn't have an exceptionally high compression ratio, and the manufacturer recommends using 92 octane, which runs smoothly with steady power output. Using 95 octane might make the engine run a bit quieter, but the actual performance improvement is minimal. Unless you're racing, there's no need to spend extra. If you choose the wrong fuel, like using a lower octane rating long-term, it could increase engine noise or even cause carbon buildup, leading to costly repairs. So my advice is to check the owner's manual for the recommended fuel, then stick with 92 octane for peace of mind and savings, while avoiding unnecessary engine strain.
