This phenomenon happens when the petroleum product reaches a low enough temperature to precipitate interlinked paraffin wax crystals throughout the fluid.
More highly distilled petroleum products have fewer paraffins and will have a lower gel point.
Anti-gel additives are sometimes added to petroleum products where cold temperature may affect their use.
The additives act to reduce the formation of wax crystals in the product, thereby lowering the pour point and the gel point of the fuel.
Anti-gel additives may not necessarily affect the cloud point.