- The temperature dropped below -15°C.
- The car was not used for a long time, it was needed in winter, and we can assume that summer diesel fuel was filled into the tank.
- Refueling at a gas station with fuel not intended for winter use.
- If it is necessary to ensure normal engine operation even at temperatures below -15°C, you should add up to 30% normal gasoline to the fuel tank, depending on what temperature is expected. Since, however, such a mixture has a bad effect on the engine, you need to refuel with normal diesel fuel again as soon as possible. An engine running on a diesel-gasoline mixture is easier to start.