According to the official vehicle manual recommendation, the Land Cruiser should use 95-octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, the Land Cruiser's fuel cap also indicates the recommended octane rating. Generally, 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 required gasoline grade, as high-compression engines can also be tuned to use lower-octane fuel. Other factors, such as ignition timing, turbocharging technology, and Atkinson cycle technology, also play a role. Generally, the higher the gasoline octane rating, 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 Land Cruiser occasionally uses the wrong gasoline grade, simply refuel with the correct grade afterward. However, prolonged use of the wrong gasoline grade can have the following effects: For vehicles designed for lower-octane fuel, using higher-octane gasoline will not cause damage, but the increased octane rating alters 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 fuel, using lower-octane gasoline can cause engine knocking. The significantly lower octane rating lowers the fuel's ignition point, causing premature ignition during the compression stroke. If combustion occurs before the spark plug fires, resistance builds up during the upward stroke. This resistance makes the engine run very unevenly. Mild knocking may only increase noise without significant engine damage, but severe knocking indicates serious engine issues. The vibrations not only affect driving stability but can also cause abnormal wear on pistons and cylinders, potentially leading to cylinder scoring in extreme cases.
