Will using 95 octane gasoline in an ES200 cause carbon deposits?
2 Answers
No. The octane rating of gasoline only indicates its anti-knock capability and has no relation to carbon deposit formation. According to the official vehicle manual for this car, the ES200 should use 92 octane gasoline. If the ES200 occasionally uses the wrong octane rating, simply switch back to the correct octane rating after use. However, long-term use of the wrong octane rating can have the following effects: For vehicles recommended to use lower octane gasoline, mistakenly using higher octane gasoline will not cause damage, but the increase in octane value can change 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 a noticeable drop in performance. For vehicles recommended to use higher octane gasoline, using lower octane gasoline can cause engine knocking. Since the octane value is much lower, the gasoline's ignition point decreases, causing it to ignite prematurely during the compression stroke. If combustion occurs before the spark plug fires during the compression stroke, resistance will develop during the upward stroke. This resistance makes the engine run very unstably. If the knocking is imperceptible, it may only increase noise without obvious damage to the engine. However, if noticeable knocking occurs, it indicates severe engine conditions, affecting not only driving stability but also causing abnormal wear on pistons and cylinders, and in severe cases, cylinder scoring. For the ES200, besides checking the recommended octane rating in the vehicle manual, you can also find it on the fuel tank cap, which will be clearly marked. Generally, the octane rating can also be determined based on the engine's compression ratio. Vehicles with a 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 use of new technologies, the compression ratio alone cannot determine the appropriate octane rating. High-compression engines can be tuned to use lower octane gasoline 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 octane rating, 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.
As an ES200 owner, I've refueled with 95-octane gasoline several times in daily use without worrying about additional carbon deposits. In fact, 95-octane is a high-octane gasoline with higher combustion efficiency, which can reduce carbon accumulation caused by incomplete combustion. The ES200's engine is finely designed, and the manual recommends 92-octane or higher gasoline, so 95-octane is a safe choice. The main causes of carbon deposits are often poor fuel quality or bad driving habits, such as prolonged idling or frequent short-distance starts, which increase engine load. Using 95-octane gasoline can actually help clean some old carbon deposits and improve power response, though at a slightly higher cost—just a few dozen yuan more per month. My experience is that regularly driving on highways and using fuel additives can both help prevent carbon deposits. Only if the engine noise becomes louder or fuel consumption is abnormal should you go to the shop to check the spark plugs and sensors.
