Should the Excelle use 92 or 95 octane gasoline?
2 Answers
According to the official vehicle manual recommendation, the Excelle should use 92 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, the Excelle's fuel cap also displays this information. Generally, the gasoline grade can also be determined based on the engine's compression ratio. Vehicles with an engine 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. However, with the application of new technologies, the compression ratio alone cannot determine the gasoline grade, as high compression ratio engines can also be tuned to use lower octane gasoline. 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 Excelle occasionally uses the wrong gasoline grade, simply switch back to the correct grade after consumption. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles designed for lower octane gasoline, using higher octane gasoline will not cause damage, but the increased octane number can alter 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 designed for higher octane gasoline, using lower octane gasoline can cause engine knocking. The significantly lower octane number reduces the fuel's ignition point, causing premature ignition during the compression stroke. If the fuel ignites before the spark plug fires, resistance occurs during the upward stroke. This resistance makes the engine run very unstably. Mild knocking only increases noise without significant engine damage, but severe knocking indicates serious engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and even cylinder scoring in extreme cases.
I've always paid attention to details about car maintenance. For the Buick Excelle, the manufacturer usually recommends using 95-octane gasoline because its engine has a high compression ratio. Gasoline with the appropriate octane rating can prevent knocking and avoid engine damage. 92-octane gasoline has a lower octane rating, and although it's cheaper, long-term use may lead to incomplete combustion, increased carbon deposits, and even affect performance. My experience is that the new car manual clearly states the recommendations, and following them is the safest approach. If you occasionally use 92-octane, it's not a big issue, but it's not recommended for long-term use. In summer, when temperatures are high, higher-octane gasoline is even more necessary for stable operation. From a technical perspective, 95-octane gasoline can also optimize fuel economy, saving a bit on fuel costs—after all, maintaining the engine well is much cheaper than repairing it. In short, using 95-octane is more reliable, especially if you frequently drive in the city or on highways.
