Seasonal fuel specifications are set out in Poland’s law on monitoring and controlling fuel quality and in a regulation issued by the climate and environment minister. The parameters change through the year to help engines operate in heat, cold and periods of sharp temperature variation.
For diesel, the key measure is the cold filter plugging point (CFPP). Summer diesel, with a CFPP of 0°C, is used from 16 April to 30 September. Transitional diesel, rated to −10°C, is required from 1 October to 15 November and again from 1 March to 15 April. Winter diesel, with a CFPP of −20°C, applies from 16 November through the end of February. The lower threshold helps prevent fuel components from crystallising and obstructing the fuel system in cold weather.
Petrol specifications vary chiefly by vapour pressure, which affects how readily fuel evaporates and how an engine starts. Summer petrol is set at 45–60 kPa from 1 May to 30 September. During the transition periods—1 March to 30 April and all of October—the range is 45–90 kPa. Winter petrol, at 60–90 kPa, applies from 1 November to the end of February and is designed to evaporate more readily in low temperatures.
Drivers do not need to change fuels or check compatibility themselves: stations are responsible for introducing the correct seasonal grade. The summer petrol limits also help reduce vapour-lock problems in hot weather, while the diesel thresholds lower the risk of filter blockage as temperatures fall.