At a certain temperature in diesel fuel crystals of paraffin which do fuel viscous so it cannot pass through the filter any more are formed. In this case say that fuel thickened. To avoid increase in viscosity of fuel, you should buy at filling stations (filling stations) fuel which corresponds to a season (summer or winter).

So, summer diesel fuel delivers you difficulties, for example, already at temperature lower than-2 °C while winter fuel keeps fluidity up to temperature of-15 °C. If at filling station there is no winter fuel, it is possible to add special depressorny additives (anti-gels) which lower parafinizatsiya temperature approximately from–8 to–10 °C in summer fuel.

At car operation with the diesel engine at low temperatures there can be problems in the following cases:

- the temperature falls below–15 °C;

- you long did not go by the car, and then again began to maintain it, but in the winter while in a tank the fuel bought in the summer is filled in;

- you bought diesel fuel at filling station that did not yet pass to sale of winter fuel.