Glycol is added to aviation gasoline to prevent freezing of petrol.
Petrol is a mixture of hydrocarbons that are volatile, meaning they evaporate easily. This is why petrol is used in cars and other engines: the fuel vaporizes and mixes with air to create a combustible mixture. However, at high altitudes, the air is much colder, and petrol can start to freeze. This can cause problems in engines, as the frozen fuel can clog fuel lines and injectors.
Glycol is a substance that has a much lower freezing point than petrol. When it is added to petrol, it lowers the freezing point of the fuel, preventing it from freezing at high altitudes. This allows aircraft to fly safely in cold weather conditions.
In addition to preventing freezing, glycol also has other benefits when added to petrol. It can help to reduce engine wear and tear, and it can also improve fuel efficiency. However, the main reason for adding glycol to aviation gasoline is to prevent freezing.