Should the Hongqi HS5 use 92 or 95 octane gasoline?
2 Answers
According to the official vehicle manual recommendation, the Hongqi HS5 should use 95 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, you can also find it indicated on the fuel tank cap of the Hongqi HS5. 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 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 gasoline grade to be used. Even high compression ratio engines can be tuned to use lower octane gasoline. This is 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 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 Hongqi HS5 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 recommended to use lower octane gasoline, using higher octane gasoline will not cause damage, but the increase in octane number will alter the fuel's ignition point, leading to delayed combustion in the engine. This means both 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. Due to the significantly lower octane number, the gasoline's ignition point decreases, leading to premature ignition during the compression stroke. If combustion occurs before the spark plug ignites in the compression stroke, resistance will arise during the upward stroke. This resistance can make the engine run very unstably. If the knocking is imperceptible, it only increases noise without significant damage to the engine. However, noticeable knocking indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring.
I've been driving my Hongqi HS5 for almost two years now. When I first got the car, I wanted to save some money and occasionally used 92-octane gasoline. However, I noticed slight jerking during acceleration on the highway, especially when climbing hills, accompanied by a buzzing engine sound. After consulting a professional technician at the 4S店, he advised me to check the owner's manual first, which clearly recommends 95-octane gasoline due to the engine's high compression ratio requiring higher-octane fuel for optimal performance. After switching to 95-octane, the difference was noticeable: the power delivery became much smoother, and the average fuel consumption dropped from 9.2L/100km to around 8.8L. Although 95-octane costs 0.4 yuan more per liter, the monthly fuel savings combined with improved performance meant the overall expense remained roughly the same. Long-term use of 95-octane also reduces the risk of carbon buildup. During the 40,000-km maintenance, the technician commented on the engine's excellent condition. My advice? Skip the 92-octane and go straight for 95-octane to protect your car and enjoy a more reassuring driving experience.
