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Why a car won’t start in cold weather

Why a car won’t start in cold weather


Cold winter days are at our doorstep and we all know how low temperatures can make it hard for us to start the car. In order to prevent potential problems, it’s good to be familiar with the main reasons why a car won’t start in cold weather, especially on freezing winter mornings.

The battery

A cold battery does not produce the same amount of power as a warm battery because the chemical reactions are slower at low temperatures. In order to start a weakened battery more easily in the morning first turn off all the electrical accessories like heating, radio, headlights etc. in order not to waste the power that the battery needs to start the car.

Check if all the terminals on the battery are clean and tight. If you notice any signs of corrosion on the terminals you’ll need to clean them with a little bit of water. If there is no sign of corrosion, make sure that the terminals are tight enough as weak connection can prevent currency flow.

Also, you might want to see your mechanic who will inspect the battery voltage and see if it needs replacement.

car won’t start


Engine oil

Check the owner’s manual to see which oil the engine constructor recommends for cold weather conditions. Modern synthetic oils perform quite well at low temperatures. However, it is very important that the oil you use corresponds to the engine specification. Multi-grade engine oils we use today are marked with two numbers. The first number, followed by the letter “W” tells us about the oil viscosity at low temperatures. The viscosity index that modern cars use today begins with 0W, 5W or 10W. Such oils are more fluent in cold weather conditions and flow more easily towards the vital parts of the engine. You can find out more about how to choose the right engine oil in one of our previous video tutorials.

Engine oil


Older cars

Fuel tanks that we see in older cars may collect moisture that freezes at low temperatures, thus blocking the fuel supply. Therefore, if you are driving an older car with a metal fuel tank, try to keep the tank as full as possible because in this way you leave less space for the water to condense on the walls and freeze. In newer cars that have plastic fuel tanks condensation is not fully eliminated either, but it is significantly reduced because the transfer of the outside temperature is much slower through plastic than through metal.

Bear in mind that some fuel components in older diesel engines tend to crystalize and clog the fuel filter, so you will need to add a recommended quantity of an appropriate additive. In their owner’s manuals, some car manufacturers recommend mixing diesel with petrol fuel depending on the outside temperature. However, if you can find no such recommendation inside the owner’s manual, it’s not wise to mix diesel and petrol fuel. With the newer generation of Euro Diesel fuel, the possibility of crystallization is significantly lower because the Euro Diesel gets multiply processed as opposed to the “old” diesel fuel.

Diesel glowplugs

Most diesel engines have a special aid for easier starts in the form of heaters, also referred to as glowplugs. Glowplugs are usually marked with a yellow symbol resembling a light bulb wire. Most modern glowplugs come from the series of “fast glowplugs” that burn for about 5 to 10 secondsThe driver needs to wait for them to turn off before starting the engine. If any of the glowplugs is not working, starting the car will be difficult, if not impossible. If more glowplugs are dead, it’s hardly likely that you will be able to start the engine at all.

Diesel glowplugs


Now that we know more about the potential reasons why a car won’t start in cold weather and how we can prevent this from happening, it is important to know also how to warm the engine properly, which we touched upon in one of our previous topics.

We hope that you find these pieces of advice useful. We will be happy to hear your suggestions, comments and questions on this topic so feel free to contact us at any time.


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