DEF Fill
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Mountain Pass
Joined: Jul 2018
Posts: 158
Likes: 2
From: Northern California
DEF Fill
We let our DEF get down the add DEF mark of 200 miles.We poured 2.5 gallons in and it came up to only 50% on the gauge. Is this correct? I was expecting the tank to be smaller. According to our truck manual (we finally checked) for our F350 we have a 7.5 gallon DEF tank. Therefore we should need to add at least another 2.5 gallons. How accurate is this guess?
Regards and Thanks
Bill
Regards and Thanks
Bill
Cargo Master
Joined: Jan 2007
Posts: 2,243
Likes: 79
From: Roman Forest, TX
I had about a half of a 2.5 gallon jug of DEF left, and I bought two more, and used them all. I don't know the percent, but the gauge was sitting on the low side of the 1/4 tank mark. Meaning it was close to empty. So easily close to 7 gallons. And it took close to 7K miles to get there. So I would say you will likely be able to put more than the 2.5 gallons in.
Laughing Gas
Joined: Oct 2017
Posts: 787
Likes: 72
From: Lansing MI
Yes, the 7.5 gallon tank (As listed in the manual, and mentioned by the OP) is about 7 gallons.
The gauge is not always that accurate, but if the OP drove the tank down to the point he go the 200 miles remaining warning, it should easily take 2 full jugs (5 gallons).
My concern these days is with the shelf life of DEF, and given that it expands when it freezes, I tend to only fill the tank half way. That seems to be enough to get me through the winter, or at least until I can find a warmer day to add some, and it keeps it keeps fresher DEF in the tank, as I am adding fresh every 6 months rather than annually.
The gauge is not always that accurate, but if the OP drove the tank down to the point he go the 200 miles remaining warning, it should easily take 2 full jugs (5 gallons).
My concern these days is with the shelf life of DEF, and given that it expands when it freezes, I tend to only fill the tank half way. That seems to be enough to get me through the winter, or at least until I can find a warmer day to add some, and it keeps it keeps fresher DEF in the tank, as I am adding fresh every 6 months rather than annually.
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Laughing Gas
Joined: Jun 2018
Posts: 939
Likes: 8
From: DFW
To avoid any spills and to use the box of blue def I just put in a box when mine shows half empty. Gauge goes to full and no spills not really that big of a deal. The gauge on my truck is not very accurate.
Mountain Pass
Joined: Feb 2007
Posts: 245
Likes: 1
From: Sandy, OR
wasn't aware of the Ford Filler Spout - the ones that came with the BlueDEF box leaked and made a mess. Combine that with the fact that the bulk cost per gallon is less at the truck stop, I just go in there and pump it full every few months. I'm sure they go through a lot of it, too; so maybe its "fresher"
New User
Joined: Jan 2006
Posts: 8
Likes: 0
DEF Dispenser
I have 2 diesels and finally gave up on the boxes. One of the local truck stops has DEF at all the pumps. Much cheaper, fresh, and shuts off when full. Found I have to be very careful putting the nozzle in or out though...it always has fluid in the nozzle and if you tip it, it runs out all over.
Posting Guru
Joined: Nov 2002
Posts: 1,222
Likes: 4
From: Texas
Used Peak DEF for a long time after getting the 450--every jug leaked. Got the Ford filler tube to use, very little spillage. Now just using the Walmart DEF at $4/jug cheaper and no leaks with their filler tube. Usually let tank go to 1/2 mark, then add a 2.5 gal jug, works for me.
Cargo Master
Joined: Oct 2015
Posts: 2,745
Likes: 72
From: West Virginia
The tank is 7.5 gallons and the jugs come in 2.5 gallon quantities. Why the gauge is marked in fourths, when thirds would be much easier is beyond me. 
One thing Ford does quite often is use whatever liquid is being pumped as coolant for the motor that is doing the pumping. In winter I never fill the DEF more than 2/3 full in order to allow for expansion and I "never" allow the level to drop below 1/3. I normally buy the WalMart DEF which is $7.99 a jug or so. I've never had a problem with the included filler neck but you do have to be careful not to crossthread it when putting it on the jug.
One thing Ford does quite often is use whatever liquid is being pumped as coolant for the motor that is doing the pumping. In winter I never fill the DEF more than 2/3 full in order to allow for expansion and I "never" allow the level to drop below 1/3. I normally buy the WalMart DEF which is $7.99 a jug or so. I've never had a problem with the included filler neck but you do have to be careful not to crossthread it when putting it on the jug.