Depends on the weather. If it even THINKS about getting below 40*F... Run 50% mixed with dino. That will be good down to about 30 or so. You are better off switching to B20 in the winter, as the 80% dino will protect you from gelled fuel all the way down to 20 below IIRC. Gelled fuel sucks. Or rather, it doesn't suck at all.

For a fun class experiment, make a bunch of different percentage samples (16 ounce water bottles are GREAT for this) and put them into the refrigerator and the freezer. My homebrewed fuel remained liquid in the refrigerator but not the freezer. But my fuel was based on WVO from soy oil. Some commercial B100 I had was based on chicken grease, and that turned into yellow jello in the refrigerator.
Thankfully, it was mixed 50% in my car at the time, b/c the overnight temps dropped to below 40!
If your fuel DOES gel, the solution is warmth. You need to warm up the entire car, including the fuel lines. Gelled fuel WILL NOT mix with diesel to suddenly "un gel" as far as I know. That is something that I should test... without using the car.
