Should Toyota Vios Use 92 or 95 Octane Gasoline?

[AmyFitz]

Toyota Vios should use 92 octane gasoline, as this fuel grade is recommended in the vehicle's official owner's manual. In addition to checking the appropriate gasoline grade in the owner's manual, the fuel cap of the Toyota Vios will also indicate the recommended grade. Usually, 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. Engines with high compression ratios can also be tuned to use lower-octane gasoline, as factors other than compression ratio—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 Toyota Vios occasionally uses the wrong gasoline grade, simply switching back to the correct grade after refueling is sufficient. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles designed for lower-octane gasoline, using higher-octane fuel 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 fuel can cause engine knocking. Since the octane number is significantly lower, the fuel's ignition point decreases, causing premature ignition during the compression stroke. If combustion occurs before the spark plug fires, resistance will develop during the upward stroke. This resistance makes 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 issues, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in extreme cases.

[Willow]

I've been driving a Toyota Vios for over three years now, and I always find 92-octane gasoline the most cost-effective. It's cheaper, saving me a few yuan per liter, which adds up to several hundred yuan per year for a full tank. The Vios' engine is actually designed for 92-octane fuel, and it's perfectly adequate for daily commuting and acceleration—there's no need to spend more on 95-octane. The manual clearly recommends 92-octane gasoline, and I've tried 95-octane before but noticed little difference, just extra expense. The key is to ensure good fuel quality by choosing reputable gas stations to avoid impurities. Overall, 92-octane is economical and poses no issues for vehicle maintenance. With gas prices rising these days, saving money is the top priority.