Should the 2011 Highlander use 92 or 95 octane gasoline?

[Camargo]

2011 Highlander should use 95 octane gasoline, as this fuel grade is recommended in the vehicle's official user manual. In addition to checking the appropriate gasoline grade in the user manual for the 2011 Highlander, it is also indicated on the fuel tank cap, which can be checked there. Typically, 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. If the compression ratio is even higher, 98 octane gasoline is recommended. However, with the application of some new technologies, the fuel grade cannot be solely determined by the compression ratio. A high compression ratio can also be adjusted to use lower octane gasoline because, besides the compression ratio, other factors such as ignition timing, turbocharging technology, and Atkinson cycle technology also play a role. Generally, the higher the gasoline grade, 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 2011 Highlander 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 number 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 a noticeable drop in performance. For vehicles recommended to use higher octane gasoline, using lower octane gasoline can cause engine knocking. Because the octane number is significantly lower, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If combustion occurs before the spark plug ignites during the compression stroke, resistance will arise during the upward stroke. This resistance makes the engine run very unstably. If the knocking is imperceptible, it only increases noise without obvious damage to the engine. However, noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring.

[LeNaomi]

I've driven this generation Highlander, and I recommend using regular 92 octane unleaded gasoline. The manufacturer designed the engine with a compression ratio matched to 92 octane, which is the most suitable. Using 95 octane long-term is also fine - the higher octane rating theoretically reduces knocking and slightly improves power, but in real-world city driving you won't feel any difference. 95 octane is usually more expensive, costing a few cents more per liter, and you can save quite a bit on fuel costs over a year - no need to waste money. The manual clearly states 92 octane is sufficient. If you use lower octane fuel like 89, it might cause engine vibration or trigger fault warnings, which would be troublesome, affecting safety and fuel consumption. Regularly checking the manual's recommendations can avoid these issues. I always prioritize 92 octane when refueling - it saves money and hassle, and the engine runs smoothly.