Diesel fuel and winter

Remember the following related to vehicle maintenance for winter

Regardless of the fuel used in a vehicle, it is always recommended to ensure that a vehicle is serviced appropriately according to its service programme. It is important to check the condition of the fuel filter and fuel system. When the fuel filter functions correctly, it will ensure that fuel can pass through the filter also in winter, and the vehicle will function as expected.

Diesel fuel and winter

The drivers of diesel vehicles must ensure that they use winter diesel fuel suitable for cold weather. If there is summer diesel in the fuel tank, it is recommended to use as much as possible of the summer diesel while the temperature allows it, and then fill up the tank with winter range diesel that can be used in cold weather. If any summer diesel fuel is left in the tank, it will reduce the properties of winter grade diesel added to the tank.

Dispensers at service stations have been marked with signs indicating whether they contain summer or winter range diesel fuel, or so-called arctic diesel fuel.

Usually, manufacturers indicate the winter properties of diesel fuel using a marking that contains two parts: the first figure indicates the cloud point and the second the plugging point.

The cloud point describes the diesel fuel's properties in cold conditions. It is a temperature in which the paraffins in diesel fuel begin to crystallise and drop to the bottom of the fuel tank, and the colour of the product changes to cloudy. The plugging point, in other words the lowest use temperature, is the lowest temperature in which fuel will pass through a filter. Filters used in vehicles differ in their retention efficiency. The differences depend on the size of the filter and its location.

Petrol and winter

The summer and winter grades of petrol differ from each other as for their vaporisation properties. In the winter time, an engine requires petrol that vaporises more easily in order to start in a lower temperature.

The petrol's vapour pressure affects its vaporisation. The vapour pressure of the winter grade is higher than that of the summer grade meaning that it will vaporise more easily. In the winter time, petrol contains more light hydrocarbon fractions that vaporise sufficiently and enable the start of a cold engine. There must also be enough hydrocarbons in the middle of the distillation range so that enough fuel is injected into the engine when driving in cold weather.

If you are new to driving a diesel vehicle, concentrate while refuelling!

You should only focus on refuelling when doing so at a service station. Safety instructions, such as avoiding speaking on the phone while refuelling, have not been issued in vain. It only takes a couple of minutes to refuel, so you should leave other things aside and ensure that you refuel using the correct fuel.

Especially those who are new to driving a diesel vehicle must stay focused during refuelling so that they do not put petrol into a diesel vehicle by accident. This is possible as a petrol fuelling nozzle can fit into the opening of a fuel tank in a diesel-powered vehicle. If a person has been driving a petrol-powered vehicle for a long time, this kind of an error may be due to “old habits”.

In case you use wrong fuel, a diesel vehicle must be transferred by pushing or towing, and the fuel system must be emptied in an appropriate manner. In such a case, it is always recommended to contact the local dealership, especially if the vehicle in question is a new diesel vehicle.

It is not possible to put diesel fuel by accident into a petrol vehicle that uses the current unleaded petrol as a diesel fuel nozzle does not fit into the opening of a fuel tank in a petrol vehicle. However, if even a small amount of diesel fuel ends up in petrol from a spare canister, for example, the petrol must be replaced so that a risk of operating disruption and engine damage is avoided.

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