Should the VV6 use 92 or 95 octane gasoline?
2 Answers
The VV6 should use 92-octane gasoline, as this fuel grade is recommended in the vehicle's official owner's manual. In addition to checking the appropriate gasoline grade in the owner's manual, the VV6's fuel cap will also indicate the recommended grade. Typically, 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 use 92-octane gasoline, while those with a ratio between 10.0-11.5 should use 95-octane gasoline. If the compression ratio is even higher, 98-octane gasoline is recommended. However, with the application of new technologies, the compression ratio alone cannot determine the appropriate gasoline grade. High-compression engines can also be tuned to use lower-octane fuel, as 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 rating 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 VV6 occasionally uses the wrong gasoline grade, simply switching back to the correct grade after consumption is sufficient. 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 both 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 is generated during the upward stroke. This resistance makes the engine run very unstably. Mild knocking may only increase noise without obvious engine damage, but severe knocking indicates serious engine issues, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, potentially leading to cylinder scuffing.
My VV6 has been running on 92-octane gasoline, and the car feels smooth with reasonable fuel consumption. The official manual recommends 92-octane or higher, so 92-octane fully meets daily needs. Although 92-octane has a slightly lower octane rating, for city driving with frequent stops at traffic lights, the engine responds quickly enough, and I've rarely encountered knocking issues. Occasionally using 95-octane for long trips makes the power delivery a bit smoother, but it's not worth the extra cost for daily use—especially with a large fuel tank, sticking to 92-octane saves a lot. Engine health mainly depends on regular maintenance, and after years of using 92-octane, I've never had any issues. In summer heat, 95-octane might offer slightly better anti-knock performance, but I stick with 92-octane for affordability and convenience.
