Can the Old Toyota Reiz Use 92 Octane Gasoline?
2 Answers
According to the official vehicle manual recommendation, the old Toyota Reiz should use 92 octane gasoline. In addition to checking the suitable gasoline grade in the vehicle manual, the old Toyota Reiz can also refer to the label on the fuel tank cap. 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 choose 92 octane gasoline, while those with a compression ratio between 10.0-11.5 should opt for 95 octane gasoline. However, with the application of new technologies, the gasoline grade cannot be solely determined by the compression ratio. Even high compression ratio engines can be tuned to use lower octane gasoline, as factors like 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 old Toyota Reiz 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 reduces 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 value, the gasoline's ignition point decreases, causing premature ignition during the compression stroke. If combustion occurs before the spark plug ignites, resistance will arise during the upward stroke. This resistance makes the engine run very unstably. Mild knocking only increases noise without obvious engine damage, but noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and even cylinder scoring in severe cases.
I used to drive an old Mark X (Reiz) and always used 93-octane gasoline. Once I tried 92-octane and felt the acceleration was weaker with noticeably slower throttle response. The V6 engine in the Mark X has a relatively high compression ratio, and the manual clearly recommends 93-octane or higher to prevent knocking and protect the engine. 92-octane has slightly lower octane rating, leading to unstable combustion under high temperature and pressure, which may cause carbon buildup or wear parts over time. Personally, I suggest following the manual's recommendation—don't save a little money at the expense of your car. Proper maintenance ensures longer lifespan and better fuel efficiency. If 93-octane is really unavailable, occasionally using 92-octane is acceptable, but don’t make it a habit. Adding some fuel additives before long trips can help mitigate the effects.
