Golf 1.4T: Should I Use 92 or 95 Octane Gasoline?

[ArabellaAnn]

The Golf 1.4T can use 95 octane gasoline. This fuel grade is officially recommended in the vehicle's user manual. In addition to checking the appropriate gasoline grade in the vehicle's user manual, the recommended fuel type is also indicated on the fuel tank cap. Generally, the fuel 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. For higher compression ratios, 98 octane gasoline is recommended. However, with the application of new technologies, the compression ratio alone cannot determine the required fuel grade, as high-compression engines 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 gasoline 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 Golf 1.4T occasionally uses the wrong gasoline grade, simply refuel with the correct grade afterward. However, prolonged use of the wrong fuel grade can have the following effects: For vehicles designed for lower-octane gasoline, using a higher-octane fuel will not cause damage, but the increased octane number may alter the fuel's ignition point, leading to delayed combustion. This can reduce the engine's power output and thermal efficiency, resulting in poorer performance. For vehicles designed for higher-octane gasoline, using a lower-octane fuel 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 will arise during the upward stroke, making the engine run very unstably. Mild knocking may only increase noise without significant engine damage, but severe knocking indicates serious engine issues, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring.