What Grade of Gasoline Should the Toyota Allion Use?
2 Answers
Toyota Allion should use 92-octane gasoline, as this fuel grade is recommended in the vehicle's official owner's manual. In addition to checking the owner's manual for the appropriate gasoline grade, Toyota Allion owners can also find this information on the fuel filler cap, which is typically labeled. Generally, 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. For higher compression ratios, 98-octane gasoline is recommended. However, with the use of new technologies, the compression ratio alone may not determine the appropriate gasoline grade, as high-compression engines can sometimes be tuned to use lower-octane fuel. Other factors, such as ignition timing, turbocharging technology, and Atkinson cycle technology, also play a role. Generally, higher-octane gasoline has a higher octane rating and better anti-knock properties. For example, 92-octane gasoline contains 92% isooctane and 8% n-heptane, while 95-octane gasoline contains 95% isooctane and 5% n-heptane. If the Toyota Allion is occasionally filled with the wrong gasoline grade, simply switching back to the correct grade after the tank is empty is sufficient. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles designed for lower-octane gasoline, using a higher-octane grade will not cause damage, but the increased octane rating can 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 a lower-octane grade can cause engine knocking. The significantly lower octane rating lowers the fuel's ignition point, causing premature ignition during the compression stroke. If the fuel ignites before the spark plug fires, resistance occurs during the piston's upward stroke. This resistance makes the engine run very unevenly. Mild knocking may only increase noise without significant engine damage, but noticeable knocking indicates severe engine conditions. The vibrations not only affect driving stability but can also cause abnormal wear on the piston and cylinder, potentially leading to cylinder scoring in severe cases.
The Toyota Allion manufacturer recommends using 92-octane gasoline, as clearly stated in the manual. The engine of this car is designed and calibrated based on 92-octane fuel, with a moderate compression ratio, making it fully compatible. I usually fill up with 92-octane when driving this car, and it performs well both on highways and in city commuting. Some people think 95-octane is superior, but it’s unnecessary—using 95-octane in the Allion won’t improve power or reduce fuel consumption; it just costs more. Of course, using 95-octane in emergencies won’t cause harm, but for long-term use, 92-octane is the most suitable, being both economical and hassle-free. Based on my experience, following the manufacturer’s recommendation is always the right choice. Moreover, gas stations often have promotions for 92-octane, making it quite cost-effective.
