I have to say that gelling is not something that you should ever have to worry about if you are buying proper winterized diesel. I have never run additives in my TDI's and made it through a very hard winter last year with many 0F and lower nights and no problems. Car was parked out side all winter.
The only times i have heard of gelling is when people buy diesel in a warm climate that doesn't sell winterized fuel and then drive north of to high elevations and endd up below freezing with the fuel.
The only times i have heard of gelling is when people buy diesel in a warm climate that doesn't sell winterized fuel and then drive north of to high elevations and endd up below freezing with the fuel.