1. It’s best not to mix different types of gasoline
Mixing gasoline types actually doesn’t have a significant impact on the car itself, but car owners should still try to avoid doing so. Gasoline is a mixture, and the octane ratings you usually see—such as 93 and 97—refer to differences in the fuel’s octane number. Mixing 93 and 97 octane gasoline will result in an octane level somewhere in between, so the effect on the engine isn’t too severe. However, to ensure your vehicle’s safety, it’s best not to mix fuel types. According to experts, car manufacturers specify clear guidelines for what type of fuel to use before a vehicle leaves the factory. The grade of gasoline you should use depends on your engine’s compression ratio. If your car is designed for higher-octane fuel and you accidentally fill it with lower-octane fuel, the engine may experience knocking, reduced power, increased water temperature, and metallic knocking noises during operation. That said, there’s no need to worry too much—just refill with the correct, higher-octane gasoline next time, and your engine should return to normal. Some drivers believe that using higher-octane fuel can boost power, but this is unnecessary. If your engine’s compression ratio doesn’t meet the required standard, even the best fuel won’t make a difference. At most, you might achieve slightly lower emissions and a bit cleaner combustion, but these effects are minimal.
2. After using methanol, ethanol, or unleaded gasoline, it’s recommended to clean the fuel system
When traveling to other places, it’s common to come across methanol, ethanol, or unleaded gasoline. These types of fuel are promoted in specific regions under national regulations. If you refuel in these areas, there’s no need to overly worry about potential harm to your car from mixing fuel types. Using these fuels won’t damage your engine, but make sure to refuel at reputable gas stations like Sinopec or PetroChina to avoid filling up at roadside stations that might sell watered-down or counterfeit, low-quality gasoline. Since both ethanol and methanol are hydrophilic and can cause the fuel to degrade when mixed with water, it’s important to have your fuel system thoroughly cleaned after using them.
3. Never mix diesel with gasoline
Some drivers, due to carelessness, end up mixing diesel and gasoline—a serious mistake. These two fuels burn differently, and mixing them can lead to the car failing to start. Attempting to force the engine to start in such a situation could result in serious damage or even total vehicle loss. If you accidentally put the wrong fuel in, contact the manufacturer or a repair shop immediately to have the fuel tank and system cleaned and the engine inspected, in order to quickly eliminate any dangers.