Should the Cadillac CT4 use 92 or 95 octane gasoline?

[McAdrian]

According to the official vehicle manual recommendation, the Cadillac CT4 should use 95 octane gasoline. In addition to checking the suitable gasoline grade in the vehicle manual for the Cadillac CT4, you can also refer to the fuel cap, which will also indicate the recommended octane rating. Generally, the appropriate 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. If the compression ratio is higher, 98 octane gasoline is recommended. However, with the application of some new technologies, the gasoline grade cannot be solely determined by the compression ratio. High-compression engines can also be tuned to use lower-octane gasoline because, apart from the compression ratio, other factors such as ignition timing, turbocharging technology, and Atkinson cycle technology also play a role. Generally, the higher the gasoline octane rating, the higher the octane value 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 Cadillac CT4 occasionally uses the wrong gasoline grade, simply switch back to the correct octane rating after the current tank is used up. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-octane gasoline, accidentally using higher-octane gasoline will not cause damage, but the increase in octane value 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. For vehicles recommended to use higher-octane gasoline, using lower-octane gasoline can cause engine knocking. Because the octane value is significantly lower, the gasoline's ignition point decreases, causing it to ignite prematurely 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 imperceptible, it only increases noise and does not cause significant engine damage. However, if noticeable knocking occurs, it indicates severe engine conditions. The vibrations not only affect driving stability but also cause abnormal wear on the pistons and cylinders, and in severe cases, can lead to cylinder scoring.