Should the K5 use 92 or 95 octane gasoline?

[SawyerMarie]

According to the official vehicle manual recommendation, the K5 should use 92 octane gasoline. In addition to checking the appropriate gasoline grade in the vehicle manual, the K5's recommended fuel type can also be found on the fuel tank cap, which will be clearly marked. Generally, 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. However, with the application of new technologies, the fuel grade cannot be solely determined by the compression ratio. Even engines with high compression ratios can be tuned to use lower-grade gasoline. This is because, besides 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 number, the higher the octane value 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 K5 occasionally uses the wrong gasoline grade, simply switch back to the correct grade after the current tank is used up. However, long-term use of the wrong gasoline grade can have the following effects: For vehicles recommended to use lower-grade gasoline, using higher-grade gasoline will not cause damage, but the increase in octane value 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-grade gasoline, using lower-grade gasoline can cause engine knocking. Due to the significantly lower octane value, the gasoline's ignition point decreases, causing premature ignition 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 imperceptible, it may only increase noise without obvious engine damage. 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.

[LuciaRose]

I've been driving my K5 for several years, always using 92-octane gasoline as recommended by the manufacturer's manual. The engine is appropriately designed for it, and the fuel consumption remains stable at around 8 liters per 100 kilometers. I've tried 95-octane a few times and noticed a slight difference in acceleration, but the difference is negligible during daily commutes and highway driving—definitely not worth the extra cost. With 95-octane costing over one yuan more per liter, I save at least fifty yuan a month, which adds up to cover a year's maintenance expenses. More importantly, sticking with the recommended gasoline long-term helps avoid combustion issues like carbon buildup, reducing maintenance hassles. Choosing reputable gas stations matters more than obsessing over octane ratings—poor fuel quality is what really harms the engine. In short, 92-octane is perfectly suited for the K5—it’s economical and reliable, with no need to overcomplicate things.

[MacAubree]

I consider myself a bit of a performance enthusiast, enjoying delving into engine details. The K5's factory design is calibrated for 92-octane gasoline, where the octane rating is just adequate. 95-octane has a higher rating, theoretically reducing knocking and noise, especially beneficial during high-temperature or heavy-load driving, such as long-distance trips or overtaking. However, if the engine hasn't been modified, the actual difference is negligible in real-world tests. I once measured fuel consumption and acceleration—results between 92 and 95 were nearly identical, making the extra cost unjustified. My advice: check the manual—if it emphasizes high-performance tuning, then use 95; otherwise, 92 is both cost-effective and eco-friendly. Regularly inspecting the air filter does more for power than octane ratings. Remember, gentle driving protects engine longevity better than high-octane fuel.

[LylaMarie]

I just got my driver's license. When buying the K5, the salesperson said to use 92 directly, as the engine is standard configuration, so no need to overthink the fuel grade. After filling up with 92, the car runs smoothly without any noticeable issues. 95 is more expensive and unnecessary; for short city drives, 92 is sufficient. The key is not to switch fuel grades arbitrarily, otherwise the engine might not adapt. The manual recommends 92, which I trust. Saving money is better than wasting it, and choosing branded gas stations ensures quality when refueling.