Is it okay to use 92-octane gasoline for the Tharu?
2 Answers
According to the official vehicle manual recommendation, the Tharu should use 95-octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, you can also find it marked on the fuel tank cap. 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. However, with the application of new technologies, the gasoline grade cannot be solely determined by the compression ratio. High compression ratio engines can also be tuned to use lower-octane gasoline because, apart from the compression ratio, 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 value 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 Tharu occasionally uses the wrong gasoline grade, simply switch back to the correct grade after consumption. However, long-term 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 value will alter the fuel's ignition point, leading to delayed combustion in the engine. This means both the engine's power output and thermal efficiency will decrease, resulting in poorer performance in practical terms. For vehicles recommended to use higher-octane gasoline, using lower-octane gasoline can cause engine knocking. Because the octane value is much lower, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If detonation occurs before the spark plug ignites during the compression stroke, resistance will arise during the upward stroke. This resistance will make the engine run very unstably. If the knocking is imperceptible, it only increases noise and does not significantly damage the engine. However, if the knocking is noticeable, it indicates severe engine conditions. The vibrations not only affect driving stability but also cause abnormal wear on the pistons and cylinders, and in severe cases, can lead to cylinder scoring.
I've been driving the Tharu for over a year using 92-octane gasoline without issues on highways or city roads. The 1.4T engine's compression ratio isn't exceptionally high, and the fuel cap indicates '95 recommended, 92 acceptable', showing the manufacturer considered different needs. However, with 92-octane, I noticeably feel less responsive acceleration at low speeds and louder engine noise when climbing. If frequently driving fully loaded on mountain roads, I'd recommend using 95-octane as its higher octane rating reduces knock risk. For daily commuting prioritizing economy, 92-octane is perfectly adequate, but stick to reputable gas stations and avoid inferior fuel from questionable sources.
