What grade of gasoline should a Mercedes-Benz C-Class use?

[LaTravis]

Mercedes-Benz C-Class should use 95-octane gasoline, as recommended in the vehicle's official user manual. In addition to checking the appropriate gasoline grade in the user manual, the Mercedes-Benz C-Class also allows you to check the fuel cap, which will indicate the recommended grade. 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 use of new technologies, the gasoline grade can no longer be determined solely by the compression ratio. High compression ratio engines can also be tuned to use lower-octane gasoline due to factors such as ignition timing, turbocharging technology, and Atkinson cycle technology. 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 the Mercedes-Benz C-Class occasionally uses the wrong gasoline grade, simply switch back to the correct grade after refueling. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-octane gasoline, using higher-octane gasoline will not cause damage, but the increase in octane rating may 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 higher-octane gasoline, using lower-octane gasoline can cause engine knocking. Due to the significantly lower octane rating, the fuel may ignite prematurely during the compression stroke. If combustion occurs before the spark plug fires, resistance will arise during the upward stroke. This resistance makes the engine run very unstably. Mild knocking may only increase noise without obvious engine damage, but severe knocking indicates serious engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring.