What grade of gasoline should a Cadillac XTS use?
2 Answers
Cadillac XTS should use 95-octane gasoline, as recommended in the vehicle's official owner's manual. In addition to checking the owner's manual for the appropriate gasoline grade, you can also find this information on the fuel tank cap, which will be clearly marked. 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-octane gasoline, while those with a compression ratio between 10.0-11.5 should use 95-octane gasoline. For higher compression ratios, 98-octane gasoline is recommended. However, with the use of new technologies, the compression ratio alone cannot determine the gasoline grade, as high-compression 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 rating 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 you occasionally use the wrong gasoline grade in a Cadillac XTS, simply switch back to the correct grade after refueling. However, long-term use of the wrong gasoline grade can have the following effects: Using a higher-octane gasoline in a vehicle designed for a lower grade will not cause damage, but the increased octane rating 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. Using a lower-octane gasoline in a vehicle designed for a higher grade can cause engine knocking. The significantly lower octane rating lowers 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 unevenly. Mild knocking may only increase noise without noticeable engine damage, but severe knocking indicates serious engine issues, affecting driving stability and causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring.
I've been driving a Cadillac XTS for over a year now and always fill it with 91 octane or higher gasoline. The owner's manual clearly states this requirement because the engine has a high compression ratio, and using lower octane fuel can easily cause knocking and engine damage. Once, I tried to save money by using 87 octane, and during acceleration on the highway, the car didn't run smoothly, and there was a slight abnormal noise from the engine. Since then, I've stuck to 91 octane, and the driving experience has been much smoother with reduced noise. Higher octane gasoline also improves combustion efficiency, saving me from frequent repairs. Although the monthly fuel cost is slightly higher, it's more cost-effective in the long run to protect my beloved car. Additionally, the XTS is a luxury vehicle, and the manufacturer's recommendation is to start with 91 octane—don't foolishly save money by using lower octane fuel.
