Should the RAV4 use 92 or 95 octane gasoline?
2 Answers
According to the official vehicle manual, the RAV4 is recommended to use 92 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, the RAV4's fuel cap also indicates the recommended octane rating. Typically, the gasoline grade can also be determined based on the engine's compression ratio. Vehicles with a 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. However, with the application of new technologies, the compression ratio alone cannot determine the appropriate gasoline grade. High compression ratio engines can still be tuned to use lower octane gasoline due to other influencing factors such as ignition timing, turbocharging technology, and Atkinson cycle technology. Generally, the higher the gasoline octane rating, 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 RAV4 occasionally uses the wrong gasoline grade, simply switch back to the correct grade after the current tank is used up. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower octane gasoline, using a higher octane grade will not cause damage, but the increased octane value 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 recommended to use higher octane gasoline, using a lower octane grade can cause engine knocking. The significantly lower octane value lowers the fuel's ignition point, causing premature ignition during the compression stroke. If combustion occurs before the spark plug fires, resistance is created during the upward stroke. This resistance makes the engine run very unstably. Mild knocking may only increase noise without significant engine damage, but severe knocking indicates serious engine conditions, affecting driving stability and causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring.
My RAV4 is the 2022 hybrid version with an engine compression ratio as high as around 14:1. Using 92-octane gasoline with lower octane rating can easily cause knocking, which makes the engine produce abnormal noises and significantly reduces power. I once tried using 92-octane fuel for a long-distance trip, and the fuel consumption soared to over 8L/100km, nearly 1L higher than when using 95-octane. Over time, the engine light even came on once, which really scared me. The manual clearly states that 95-octane fuel is recommended, as it suits the high-compression-ratio design, reducing wear and carbon buildup. I always stick to 95-octane now, and the car accelerates smoothly with better fuel efficiency, usually around 7L/100km. Even though the fuel price is higher, the savings on maintenance costs make it more cost-effective in the long run. Don’t risk big trouble for small savings—safety first!
