Should the Terra use 92 or 95 gasoline?
3 Answers
The Terra should use 92-octane gasoline, as this fuel grade is recommended in the vehicle's official user manual. In addition to checking the appropriate gasoline grade in the vehicle's user manual, it is also indicated on the fuel tank cap. Usually, the fuel 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. If the compression ratio is higher, 98-octane gasoline is recommended. However, with the use of some new technologies, the compression ratio alone cannot determine the appropriate gasoline grade. A high compression ratio can also be tuned to use lower-octane gasoline because, apart from the compression ratio, 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 Terra occasionally uses the wrong gasoline grade, simply switching back to the correct grade after use is sufficient. 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 number will change the fuel's ignition point, leading to delayed combustion in the engine. This means the engine's power output and thermal efficiency will decrease, resulting in poorer performance. For vehicles recommended to use higher-octane gasoline, using lower-octane gasoline can cause engine knocking. Because the octane number is too low, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If the fuel ignites before the spark plug fires during the compression stroke, resistance will occur during the upward stroke. This resistance makes the engine run very unstably. If the knocking is mild, it only increases noise and does not cause significant damage to the engine. However, if the knocking is severe, it indicates serious engine conditions, affecting not only driving stability but also causing abnormal wear on the pistons and cylinders, and in severe cases, cylinder scoring.
I drove a Terra for three years, and the official recommendation for this car is to use 92-octane gasoline, which I always followed. The engine ran smoothly, was fuel-efficient, and economical. 92-octane fuel is cheaper, saving over one yuan per liter compared to 95-octane, which adds up to significant savings over time. The Terra's engine has a relatively low compression ratio, so using higher-octane 95 fuel isn't necessary unless you frequently drive on highways or mountain roads, where it might offer slightly better power response. But for city driving, 92 is more than enough. I also made sure to maintain consistent fueling habits—avoiding switching between 92 and 95 to prevent engine knocking or adaptation issues, keeping the engine healthier. In short, 92-octane offers the best value for money, and during maintenance, don’t be fooled into switching to other premium fuels—keeping it simple and hassle-free is the way to go.
As an automotive enthusiast, I've studied the engine design of the Terra. It's based on a naturally aspirated engine with a relatively low compression ratio, making 92-octane fuel perfectly suitable. Using 95-octane is unnecessary and just a waste of money. 95-octane is more appropriate for high-performance vehicles or turbocharged models to reduce knocking, but the Terra isn't that type of vehicle. I've personally tried 95-octane a few times and noticed slightly quicker acceleration, but there was no improvement in fuel efficiency—just a waste of budget. The manual clearly recommends 92-octane, so I stick with it, and with proper maintenance, the car performs well. To elaborate, gasoline octane ratings indicate the fuel's resistance to knocking—higher numbers mean better anti-knock properties, but regular SUVs don't require it.
