What grade of gasoline should a Mercedes-Benz E300 use?
3 Answers
The Mercedes-Benz E300 should be fueled with 95-octane gasoline, as recommended in the vehicle's official owner's manual. In addition to checking the appropriate gasoline grade in the owner's manual, you can also find this information on the fuel tank cap, which will be clearly marked. 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 higher, 98-octane gasoline is recommended. However, with the application of new technologies, the gasoline grade cannot be solely determined by the compression ratio. Engines with high compression ratios can also be tuned to use lower-octane gasoline due to other influencing factors such as ignition timing, turbocharging technology, and Atkinson cycle technology. 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 Mercedes-Benz E300 is occasionally fueled with the wrong gasoline grade, simply switch back to the correct grade after the current tank is used up. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles designed for lower-octane gasoline, using a higher grade will not cause damage, but the increased octane number 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 designed for higher-octane gasoline, using a lower grade can cause engine knocking. The significantly lower octane number lowers the fuel's ignition point, causing premature ignition during the compression stroke. If combustion occurs before the spark plug fires, resistance is created 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.
I've been driving a Mercedes-Benz E300 for several years and always use 95-octane gasoline. This car's engine has high requirements, and 95-octane fuel provides good combustion efficiency, making the ride smooth and quiet. Once when I used 92-octane fuel, I noticed slight engine vibrations and unusual noises, so I quickly switched back to 95-octane, and everything returned to normal. The manual recommends 95-octane as the minimum, with 98-octane being better but more expensive. I also maintain the engine regularly, such as checking the fuel system every 5,000 kilometers to prevent impurities from affecting performance. Remember not to mix different fuel grades—filling up at one gas station is more reliable. Long-term use of lower-octane fuel may damage spark plugs or fuel injectors, increasing repair costs. In short, using 95-octane in the E300 is the most hassle-free option, delivering strong performance while protecting the car.
I often help people with car repairs and have encountered many Mercedes-Benz E300 cases. I recommend using 95-octane gasoline. The engine is precisely designed, and higher-octane fuel can prevent knocking issues and avoid piston wear. The owner's manual specifies a minimum requirement of 95 RON, equivalent to domestic 95-octane. Using lower octane may trigger the check engine light or reduce power output. In similar cases, I suggest checking if the fuel pump and sensors are functioning properly. While using 98-octane can improve responsiveness, 95-octane is sufficient for daily use. Regularly cleaning the fuel tank is also crucial to prevent impurities from affecting the fuel system. Avoid refueling at small gas stations where quality is hard to guarantee. Mercedes maintenance emphasizes attention to detail, and using the correct fuel grade is fundamental care that helps the car run longer and more smoothly.
