What is the Point at Which Motor Oil Freezes?

Motor oil doesn’t freeze because it doesn’t crystallise or get solid at any temperature. But at freezing temperatures, motor oil starts to get thicker and loses its ability to flow through the engine and keep it from getting too hot. This makes it more likely that engine parts will break when it’s cold outside.

Oil is made from petroleum, so it won’t freeze solid even when it’s cold. It will, however, lose its ability to flow when the temperature drops. For example, diesel oil that has been cooled below 0 degrees Fahrenheit will change colour and texture, becoming white and solid enough that it won’t flow through the engine.

This change is caused by the waxes that were dissolved in the oil settling out. Gasoline doesn’t have these waxes, which is why it doesn’t react as much to cold weather as motor oils made from petroleum.

Choose a light, winter-grade oil in the winter to avoid engine problems caused by thickened oil. Lighter oils move through the engine more easily when it’s cold, while thicker oils may get stuck in the engine and make it hard to start the car in the winter.

On the label of the bottle, you can find information about how thick the oil is. The letter W in the name of an oil means that it is good for driving in the winter.

Another way to solve this problem is to use synthetic oil, which, according to the motor oil company Mobil India, doesn’t get thick when the temperature drops to -40 degrees Celsius. On the other hand, as crude oil cools, it gets very thick and tar-like.

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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