Note the last sentence. Copied from wiki.
Additives[edit]
Retail stores offer a number of additives that will lower the CFPP of diesel oil. These will only be effective when added above the Cloud Point as the additive needs to mix well with the diesel oil - ideally the additive should be added at the gas station when the fuel is still warm from the storage tanks.
The additives will not prevent the diesel from developing wax particles but these are hindered from melding together to form larger wax flakes that can clog up the fuel filter. In comparison with blending diesel fuel with lighter fuel (that has a lower CFPP) the usage of additives is cheaper and gas stations in cold regions offer diesel fuel with additives at no extra cost (see below). If the gas station offers winterized diesel you should not add additional additives - the fluid characteristics may deteriorate due to incompatible additives and the CFPP enhancement may be reversed