Should the Buick Regal use 92 or 95 octane gasoline?
2 Answers
According to the official vehicle manual recommendation, the Buick Regal should use 95 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, you can also find it on the fuel tank cap, which will also be indicated. 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 choose 92 octane gasoline, while those with a compression ratio between 10.0-11.5 should choose 95 octane gasoline. However, with the use of some new technologies, the gasoline grade cannot be determined solely by the compression ratio. A high compression ratio can also be adjusted to use lower-grade gasoline because, in addition to the compression ratio, 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 Buick Regal occasionally uses the wrong gasoline grade, simply switch back to the correct grade after use. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-grade gasoline, using higher-grade gasoline will not cause damage, but the increase in octane number will change the fuel's ignition point, leading to delayed combustion in the engine. This means the engine's power output and thermal efficiency will decrease, and the actual feedback experience is reduced performance. For vehicles recommended to use higher-grade gasoline, using lower-grade gasoline can cause engine knocking. Because the octane number is too low, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If the fuel ignites before the spark plug fires during the compression stroke, resistance will occur during the upward stroke. This resistance will make the engine run very unstably. If it is mild knocking, it only increases noise and does not significantly damage the engine. However, if there is obvious knocking, it indicates that the engine's condition is very severe. The vibration not only affects driving stability but can also cause abnormal wear on the piston and cylinder, and in severe cases, cylinder scoring.
I drive a Buick Regal that I bought a few years ago, mainly for daily commuting. Regarding whether to use 92 or 95 octane gasoline, the Buick official manual actually recommends 95 octane or higher. Higher octane fuel helps prevent engine knocking under high load, ensuring smoother operation and stronger power output. 92 octane is cheaper, saving a few cents per liter. I tried it once and found it acceptable for short city trips without major issues, but on the highway, I noticed slower throttle response and some unusual noises at higher RPMs. Long-term use of 92 octane may increase carbon buildup or accelerate wear, leading to higher repair costs. I suggest checking your manual or consulting a dealership and prioritizing 95 octane to maintain your car's health—don’t skimp where it matters most. After all, a good car isn’t cheap, and proper maintenance ensures peace of mind and safety.