Should the Land Cruiser use 92 or 95 octane gasoline?

[VanRachel]

The Land Cruiser can use 95 octane gasoline. This gasoline grade is recommended in the vehicle's official user manual. In addition to checking the appropriate gasoline grade in the vehicle's user manual, the Land Cruiser also has it indicated on the fuel tank cap. You can usually determine the suitable gasoline grade 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 higher, 98 octane gasoline is recommended. However, with the application of new technologies, the compression ratio alone cannot determine the gasoline grade, as high-compression engines can also be tuned to use lower-octane gasoline. Other factors, 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 Land Cruiser 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 designed for lower-octane gasoline, using higher-octane gasoline 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 gasoline can cause engine knocking. The significantly lower octane number lowers the fuel's ignition point, causing premature ignition during the compression stroke. If combustion occurs before the spark plug ignites, resistance will be encountered during the upward stroke. This resistance makes the engine run very unstably. Mild knocking only increases noise without significant engine damage, but severe knocking indicates serious engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring.