Water freezes at 32-degrees Fahrenheit.  Gasoline also freezes. However, there is not a single temperature you can assign to gasoline when it comes to freezing. You can’t say that gasoline will freeze at 70-degree-below-zero Fahrenheit, though that may represent a temperature where some gasoline mixtures will freeze. The point is that, in spite of the ability to withstand the extreme colds a Johnsburg winter will throw at it, fuel lines that carry the gasoline from the gas tank to the engine’s carburetor or fuel injectors can freeze.

If the fuel line freezes, the gasoline, liquid or otherwise, may not be able to pass. The engine will starve for fuel and won’t run.

The reason gasoline mixtures freeze at different temperatures is that all gasoline mixtures are not the same. Water is made of two hydrogen atoms to one oxygen atom – in other words, H2O. But different gasoline mixtures have different additives. Some are made with ethanol. The hydrocarbons in gasoline can crystalize but, with differing molecules in gasoline mixtures, the point where it freezes varies.

So, how do fuel lines freeze if the gasoline won’t freeze until much lower temperatures than we generally see in the McHenry area?

The problem when fuel lines freeze on a cold Johnsburg winter morning probably isn’t that the fuel froze. Rather, it’s probably that water vapor in the fuel lines froze thereby blocking the fuel line.

To keep fuel lines from freezing, there are steps you can take. They include:

• Keep the fuel tank as full as possible – when the fuel tank is full there is less room in the fuel system for water vapor.
• Keep your battery fully charged – it may take a little longer to start the engine if the fuel line is partially blocked and a fully charged battery will help you to try starting the car long enough for the fuel to work its way through the fuel line.
• Use an additive in your fuel tank – a fuel line antifreeze. A fuel line antifreeze, such as HEET, absorbs moisture in the fuel tank and keeps it from freezing in the fuel line.