Should the CT5 use 92 or 95 octane gasoline?

[IsabelLynn]

The Cadillac CT5 requires 95 octane gasoline, as per official specifications. The CT5 is a mid-size sedan under the Cadillac brand, officially launched on November 18, 2019. For the 2022 model year, the 28T Premium, Platinum, Fashion, and Luxury (standard version) variants measure 4924/1883/1445 mm in length/width/height, with a wheelbase of 2947 mm. Powering the Cadillac CT5 is a 2.0T variable-cylinder turbocharged engine, delivering a maximum power of 174 kW and peak torque of 350 N·m, while meeting the China VI emission standards. The transmission system is paired with a 10-speed automatic manual transmission. In addition to checking the appropriate gasoline grade in the vehicle's manual, you can also find it indicated on the fuel tank cap. Typically, 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. 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 gasoline grade. High compression ratio engines can also be tuned to use lower octane gasoline because, besides the compression ratio, other factors such as ignition timing, turbocharging technology, and Atkinson cycle technology also play a role. Using 95 octane gasoline significantly reduces engine vibration compared to 92 octane. 95 octane gasoline burns more completely than 92 octane, resulting in less carbon buildup in the engine and stronger vehicle performance due to more thorough combustion. Different octane ratings lead to varying anti-knock properties. Gasoline is a mixture produced by adding a certain amount of anti-knock agents to the same base gasoline, resulting in gasoline with different anti-knock performances. Different gasoline components, such as straight-run gasoline, catalytic cracking gasoline, and catalytic reforming gasoline obtained from petroleum refining, are refined and blended with high-octane components, primarily used as fuel for spark-ignition internal combustion engines in vehicles. If the Cadillac CT5 occasionally uses the wrong gasoline grade, simply switching back to the correct grade after use is sufficient. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles recommended to use low-octane gasoline, using high-octane gasoline will not cause damage, but the increase in 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. For vehicles recommended to use high-octane gasoline, using low-octane gasoline can cause engine knocking. The significantly lower octane rating lowers the gasoline's ignition point, causing premature ignition during the compression stroke. If combustion occurs before the spark plug ignites, resistance is generated during the upward stroke. This resistance makes the engine run very unstably. If the knocking is imperceptible, it only increases noise without obvious damage to the engine. However, noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in severe cases.

[VonMary]

Having driven a CT5 for over a decade, I highly recommend using 95-octane gasoline as your first choice. This car's engine has a relatively high compression ratio, and 95-octane fuel provides sufficient octane rating to reduce knocking caused by premature ignition, protecting the cylinder block and pistons. While 92-octane is cheaper, its lower octane rating may lead to engine vibration, increased noise, and reduced longevity with prolonged use, making repairs more costly in the long run. The most reliable reference is the user manual—CT5 manuals typically specify a recommendation of 95-octane or higher. Don't compromise safety to save a few bucks. Using 95-octane regularly ensures smooth engine operation and peace of mind, especially on long trips. Occasionally using 92-octane in an emergency is acceptable, but making it a habit can lead to serious issues.