What Octane Gasoline Should the Volkswagen Talagon Use?

[Tom]

The Volkswagen Talagon with the 2.0T four-cylinder engine requires 98-octane gasoline, while the six-cylinder version can use 95-octane gasoline. These octane ratings are recommended in the vehicle's official user manual. In addition to checking the suitable octane rating in the user manual, you can also find it on the fuel tank cap, which is usually labeled. Typically, the octane rating 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, those between 10.0-11.5 should use 95-octane gasoline, and those with a higher compression ratio should use 98-octane gasoline. However, with the use of new technologies, the octane rating cannot be solely determined by the compression ratio, as engines with high compression ratios 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 octane rating, 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 Volkswagen Talagon occasionally uses the wrong octane rating, simply switch back to the correct one after the current tank is used up. However, long-term use of the wrong octane rating can have the following effects: For vehicles designed for lower-octane gasoline, using higher-octane gasoline will not cause damage, but the increased octane number 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 designed for higher-octane gasoline, using lower-octane gasoline can cause engine knocking. The significantly lower octane number reduces 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 unevenly. Mild knocking may only increase noise without significant 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.