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DEF QUESTION

SCopeland

SCopeland

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Just traded in my 08 DRW for 2020 SRW, have owned Diesels for ever, but this is my first one with DEF. The salesman said not to fill the DEF all the way, only go to 3/4 full. I asked why, he said that is what he was told that on Rams you only fill it to 3/4. And this is at a Ram Dealership. The service dept was zero help. Anyone know why he would say that??? TIA
 
I currently have 70,000 miles on my 2023 and have always filled up at truck Truck Stops and have not had a problem. I am curious to see if anyone else has any more information regarding this.
 
SCopeland said:
Just traded in my 08 DRW for 2020 SRW, have owned Diesels for ever, but this is my first one with DEF. The salesman said not to fill the DEF all the way, only go to 3/4 full. I asked why, he said that is what he was told that on Rams you only fill it to 3/4. And this is at a Ram Dealership. The service dept was zero help. Anyone know why he would say that??? TIA
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You can fill it but don’t overfill it. There was a period in time where if you filled it to the cap it would send the sonic sending unit for the gauge into a fit. I’m not sure if any ecm updates ever solved that issue. When I ran def I always bout the 2.5 gallon cubes from Walmart and when the light came on for low level I’d just add another and not fill it so it was always fresh. Never a problem.
 
Especially in winter. If you are in an area that gets cold enough, DEF can freeze without causing a problem, but frozen water expands and a full tank will rupture which is something you do not want to have to mess with.
 
Overfilling is the issue. Truck stop DEF pumps won’t overfill and generally have very fresh DEF. I try to only use pump DEF.

wrvond said:
Especially in winter. If you are in an area that gets cold enough, DEF can freeze without causing a problem, but frozen water expands and a full tank will rupture which is something you do not want to have to mess with.
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This is only an issue if you overfill the tank, a full tank has expansion room and won’t rupture.
 
wrvond said:
Especially in winter. If you are in an area that gets cold enough, DEF can freeze without causing a problem, but frozen water expands and a full tank will rupture which is something you do not want to have to mess with.
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Don't have to worry about it freezing live in No Florida. Eventually it will go on a weight loss program.
 
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