Is it worth it to add a davco?

[Hammerhead]

(04-16-2018 )dhirocz Wrote:  I wasn't aware of that. I figured gelled fuel was gelled fuel...

I don't see how adding a davco could hurt. My apu has an Arctic setup on it as well. If I'm not mistaken, it doesn't recirculate fuel, but has coolant lines that loop through the tanks to keep the fuel warm. So between the davco and the apu, I should be OK for intermediate cold if the davco was heated if the lines aren't that big of a deal.

Out of curiosity, how cold would it have to be to gel up the fuel lines?

#2 diesel has paraffin wax in it, that's why it burns hotter and produces more BTU, which translates to more power/efficiency.
When it gets cold, the wax congeals in standing volumes, like your fuel tanks. But as soon as it starts moving, as it's being drawn into the fuel lines, the fluid motion and friction breaks the wax back up. The motion of going down the road actually helps keep fuel from gelling too bad.
I don't know the exact temperature, and different areas have different fuel formulas and all of that will play a part in the actual gel point, but it not only has to be cold, it also has to be stagnent.
The real problem with #2 comes into play when the fuel tries to pass through the filter media. Although the wax breaks up and re-enters suspension during flow, it doesn't break up fully. It is these small clumps that plug up the pores of the filter media disrupting the liquid portion of the fuel flow, starving the engine.
Most places actually cut their #2 fuel in colder climates by some percentage. All of these facilities have filters as well, and changing plugged filters constantly disrupts their ability to move the quantity of product required.
If your APU runs coolant through lines in your fuel tanks, you would most likely be fine. If it's going to get really cold, cut it with 10-20% #1 fuel. #1 fuel has no wax, that's why it doesn't gell filters.
Most people that have fuel issues and blame #2 actually have condensation issues, so it actually water, not fuel. When it gets cold, fill your fuel tanks AT THE END OF THE DAYS RUNNING! Your fuel is warm. The air in the fuel tank is warmer than the outside air. Exactly what happens to an ice cold beer bottle on a hot summer day happens...backwards, inside your fuel tanks! Fill them, and the condensation can't form on the inside wall and contaminate your fuel!
Now 871 and older engines return more fuel volume than 2250 and later engines, so without the heat transfer from the engine to the fuel tanks to help keep cold fuel from gelling when it hits the filter media, the common rail engine guys should double the #1 percentage, depending on temperature of course. I try to run #2 as much as I can. It isn't available in most of Canada in the winter, so I will load up before I cross the border, because I can notice a difference in power/efficiency even at 50/50. If it's going to be -30°C or colder, then I make sure to leave room to cut it at the end of the day.