I am just curious if there is any reason to keep the DEF tank at a high level during winter or if it is OK to let it get low before filling. I think mine is at 33% full, which means I have at least another month before I need to fill it. I filled it on the first fuel fill after getting the truck, and have about 5,000 miles since then. Can probably go another 2K before it is empty, putting it well into January. The station I have been filling at, that has had diesel for under $4 a gallon doesn't have DEF at the pump, otherwise I would have filled it last night. I can always make a side trip to fill it, but would like to wait if I can.

 

I don't see any issue. I ran my Cummins that way. I just filed it when it got down to about a 1/4, never a problem. Many a time it would get to the warning light. I plan on doing the same with this one.

 

Its fine, just dont top it off right to the cap. there has to be room for expansion. the stuff does freeze and is why there is a heater in the tank.

 

I run my DEF down to just below half, then throw in a 2-1/2 gallon jug, regardless of the temperature.

 

Being aqueous, when it freezes it will expand. Here in AK, I keep the tank around half full.

 

It freezes at 12°F and as long as it is not overfilled, the tank has expansion room built in to accommodate for freezing. I assume you fill with the corrugated nozzle that comes with the jug which won't let you overfill unless you really work at it. If you fill at a gas station, then you have to be more careful.

Generally, I add it at convenience. If I am at 1/2 tank, I add one jug, if I am at 1/4, I add 1 or 2 jugs. As you stated, you don't use a lot of DEF - (unless towing) so a tank lasts a long time.

The heaters only thaw DEF in the immediate area in the pump module for current usage - they do not thaw the entire tank.

 

Related to winter DEF operations, I recently had a weird error happen that I'm sure is related to the DEF freezing. On my recent hunt in the mountains, after evening temps dropped to single digits, I got the 500 mile DEF warning, and the level showed 0.8g on Torque. Wasn't worried, but oddly when I got back down to where temps were around freezing, the level jumped up to over 2 gallons. However, the warning didn't clear. I got home, and the DEF level stay about 2g with the warning still counting down on mileage left (just over 200 miles). I decided to top off the tanks to see what happens, and I got a 2.5g jug barely in it. Good news is that the warning cleared after a short time of idling around the property when I washed and cleaned out the truck. No clue why the warning didn't clear once the DEF thawed and the tank level reported about 1/2 full.

 

Your '14 is not the same as the OP (or mine being a '19) with respect to the DEF level sensor. They revised and (much needed) improved the DEF level sensor setup starting in 2017. On the '16 and older, you can run into issues with filling before it requests; and it needs to see enough of a change to register a 'fill event' and clear the code. Sometimes they can get hung up and you have to perform the drive cycle to clear it. Generally speaking (generally) - on those, you wait till it says fill, then add 5 gallons and it clears. Tops offs seem to cause more confusion. Again, general terms.

 

Understood. Different Gen trucks, and also understand that on my Gen you should wait until the warning before filling. That’s what I normally do, but in the case I described, refilling was my best shot at getting the relatively dumb system to realize it really wasn’t low on DEF. It worked.

 

Yep I would have done the same as you in your situation - agree 100% and very glad it worked

 

I ran 150,000 miles on my 2011 6.7L truck and always filled up around 1/2 tank. Only twice in 150,000 miles did I see the 500 miles to empty.
I ran 100,000 miles on my 2015 6.7L truck and always filled up around 1/2 tank and only saw the 500 miles to empty once.
I never had any problems with my DEF system. I don't think it matters about running it till it's empty.

since about 2015. There have been enough DEF pumps at fuel stops, I've not bought a jug of DEF since. I always fill up at the pump, when it's convenient. If I'm at a station that has DEF at the pump and I'm under 1/2 tank. I top off.
My 2017 truck and my current 2020 trucks both held/hold 7.5 gallons of DEF. And I've never let them get low enough to send me a 500 mile to empty message.

As far as the original poster's question. I would not over fill during the winter months. You don't want DEF fluid in the filler tube of your tank. It can freeze at 13° and expand and crack your filler tube. I usually fill my tank in early December before we get really cold in my area. If I happen to put too much in, I've consumed some of it and hopefully below the filler tube by time we hit cold temps that would freeze DEF. and by time I need DEF again, I'm usually past the really cold January temps.

 

Not worried about filling it too much, just want to be sure that if it gets too low that the heater wont be damaged when it does get too cold out. I want to see how many miles the truck gets per tank, otherwise would have already refilled it.

 

run it until less then <200 to empty regardless of weather conditions works well for me.

If you fill with the ford filler spout even in freezing temps you cannot go wrong as it will allow for the expansion.

If towing in freezing temps and you fill at the truck stop, it will be fine since you are using def at pretty high rate and the level will drop quickly, unless you turn around and park for the night that is.