What grade of gasoline should a Mercedes-Benz G-Class use?
2 Answers
Mercedes-Benz G-Class vehicles should use 95-octane gasoline, as this fuel grade is recommended in the official vehicle owner's manual. In addition to checking the appropriate gasoline grade in the owner's manual, Mercedes-Benz G-Class owners can also find this information on the fuel filler 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 use of new technologies, the compression ratio alone cannot determine the appropriate gasoline grade, as high compression ratios can also be adjusted 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 octane number, 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 a Mercedes-Benz G-Class vehicle occasionally uses the wrong gasoline grade, simply switching back to the correct grade after use is sufficient. However, prolonged use of the wrong gasoline grade can have the following effects: Using a higher-octane gasoline in a vehicle designed for a lower octane 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 results in reduced engine power and thermal efficiency, with the practical effect being poorer performance. Using a lower-octane gasoline in a vehicle designed for a higher octane can cause engine knocking. The significantly lower octane rating reduces the fuel's ignition point, causing premature ignition during the compression stroke. If combustion occurs before the spark plug fires, resistance will develop during the upward stroke. This resistance makes the engine run very unevenly. Mild knocking may only increase noise without significant engine damage, but 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.
My Mercedes-Benz G-Class has been running for almost three years now. I always strictly follow the owner's manual when refueling, which clearly recommends 95-octane gasoline. My G63 is the high-end version with a turbocharged engine design that requires at least 95-octane fuel to prevent knocking issues. Using 98-octane makes it run smoother, but 95-octane is sufficient for daily use and more economical. I remember once during a business trip when only 92-octane was available at a small gas station—after filling up, the engine shook violently. The mechanic said long-term use of low-octane fuel could wear out the piston seals. Now I only go to major brand gas stations for 95-octane and always check the octane label before refueling. It's not worth saving a few bucks on fuel only to ruin the car's performance. Driving this car requires attention to detail, and regular maintenance helps avoid problems.
