Should BYD Song Use 92 or 95 Octane Gasoline?

[LaLogan]

BYD Song 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 user manual, the fuel cap of BYD Song will also indicate the recommended grade. Generally, the gasoline grade 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. If the compression ratio is higher, 98 octane gasoline is recommended. However, with the application of new technologies, the compression ratio alone cannot determine the gasoline grade, as high compression ratio engines can also be tuned to use lower octane gasoline. 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 BYD Song 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 designed for low octane gasoline, using a higher octane grade will not cause damage, but the increased octane number may alter the fuel's ignition point, leading to delayed combustion in the engine. This reduces the engine's power output and thermal efficiency, resulting in poorer performance. For vehicles designed for high octane gasoline, using a lower octane grade can cause engine knocking. Due to the significantly lower octane number, the gasoline may ignite prematurely during the compression stroke. If combustion occurs before the spark plug fires, resistance will be 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 conditions. The vibrations not only affect driving stability but can also cause abnormal wear on pistons and cylinders, and in extreme cases, cylinder scoring.

[OVivian]

I've been driving a BYD Song, and this issue is crucial. As an owner, I've thoroughly studied the manual, which clearly states that 92 octane unleaded gasoline is recommended. The Song's engine compression ratio isn't particularly high, so the octane rating of 92 gasoline matches perfectly, ensuring stable combustion and efficient performance. In theory, 95 octane gasoline has a higher octane rating, which can reduce the risk of knocking, but it's completely unnecessary for everyday driving, especially since the Song is a hybrid with typically lower engine loads. Moreover, 95 octane gasoline is significantly more expensive than 92, making it a waste of money. I tried using 95 octane for a few months and noticed a slight improvement in throttle response, but it was barely noticeable, and there was no significant difference in fuel consumption. Eventually, I switched back to 92 octane to save money and drive with peace of mind. Additionally, in city traffic with frequent stops and starts, the 92 octane runs smoothly without any issues. Remember to regularly check the fuel filter, as keeping it clean is important. If you accidentally fill up with 95 octane, don't panic—the engine won't be damaged immediately, but long-term use might increase carbon buildup. In short, just follow the manufacturer's recommendations and avoid the hassle of higher-octane fuels.