What Octane Gasoline is Suitable for the Highlander?

[SanDylan]

Models of the Highlander equipped with the 8AR-FTS turbocharged engine should use 95 octane gasoline, while those with the A25D naturally aspirated engine should use 92 octane gasoline. These octane ratings are recommended in the vehicle's official user manual. In addition to checking the appropriate gasoline octane in the user manual, you can also find it on the fuel tank cap, which will be clearly marked. Generally, the octane rating 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, those between 10.0-11.5 should use 95 octane, and if the compression ratio is higher, 98 octane gasoline is recommended. However, with the application of new technologies, the octane rating cannot be solely determined by the compression ratio. High compression ratio engines can also be tuned to use lower octane gasoline. This is 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 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 Highlander occasionally uses the wrong octane gasoline, simply switch back to the correct octane after the tank is empty. However, long-term use of the wrong octane gasoline 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 number may alter the fuel's ignition point, leading to delayed combustion in the engine. This can reduce the engine's power output and thermal efficiency, resulting in poorer performance. For vehicles recommended to use higher octane gasoline, using lower octane gasoline can cause engine knocking. Due to the significantly lower octane number, the gasoline's ignition point decreases, causing premature ignition during the compression stroke. If combustion occurs before the spark plug fires, resistance will be generated during the upward stroke. This resistance can make the engine run very unstably. If the knocking is mild, it may only increase noise without obvious damage to the engine. However, severe knocking indicates serious engine conditions, affecting not only driving stability but also causing abnormal wear on the pistons and cylinders, and in extreme cases, cylinder scoring.