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'25 DEF tank size
- Thread starter regal2800
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The owners manual has it at 7.5 gallons.
That is alot of DEF , especially in a tank that shouldn't be allowed to get any where near empty. Is the def tank commensurate with the diesel tank and that was increased as well? Now curious why there would be a need to carry that much and all the added weight. How is 5 gallons not enough?
Great White North Eh
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I bet if you hook-er heavy it will become clear … if I had to guess they didn’t calibrate them to drink less.
Fair enough!! I haven't done that with my 2020 for any distance yet.
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With the increased DEF useage, which is good since that means less EGR, a bigger tank would be really nice. The 5.5 gallon tank on my 2022 was too small for me with the increased DEF usage over the 2018.
Kudos to Ram on this change.
Nothing wrong with letting a DEF tank get near empty.
I haven't done any heavy towing yet, but my def usage is way down. 1600 miles and im not even at 3/4 on the gauge. my '19 would have been much lower by now. The engine is either using the same amount or less, at least based on what ive have seen so far.
I have been studying the same megacab truck that you have.
From what is being posted, that truck has ~ ( 30 gallon fuel tank ) x ( ~ 20 mpg ) ~ 500 - 600 mile range.
That ~ 500 - 600 mile range is very similar to what is being reported in another thread for ~ 1 gallon of DEF use.
I just drove 4544 miles, I use between 7.25-7.50 gallons of Def, of those miles less than 200 were city driving, several fuel stops in KS & CO the diesel fuel was B20 
with Loves being the highest priced diesel fuel on my whole trip Maverick had some of the lowest prices except 2 times where Wally was cheaper....
with Loves being the highest priced diesel fuel on my whole trip Maverick had some of the lowest prices except 2 times where Wally was cheaper....
H3LZSN1P3R
You're doing it wrong
You cant go by the gauge for comparison because its not the same size tank and the level sensor may not read the same.
AH64ID:
My statement was made going off the way the def dry's and was more a personal thought, although my statement didn't actually read that way
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I’ve never been too concerned with DEF tank level, just its age.
There is the potential for crystallization with a lower tank volume, but the tank is sealed so it likely has high humidity in heat reducing the crystallization. You also get more splashing which would knock any crystallization down too.
If it’s really a concern you can add some distilled water and dilute the DEF. DEF is 32.5% but the truck doesn’t care as long as it’s above 22%. less than 26% is where I’ve seen a slight increase in DEF consumption, so 26-28% is a good target.
H3LZSN1P3R
You're doing it wrong
Also as soon as you fill it the crystals get cleaned up.
johnmyster
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Lots of wild imaginations about what happens inside of a DEF tank. Everyone has their theory about that tank of magic.
Wow - ( - 10 C ) isn't even very cold. In MN the women would not even be wearing a jacket to go out.
Great White North Eh
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Mmm… is that because they stop shaving parts? …har har…sorry had too. DEF just ain’t designed for anywhere you might have to scrape your windshield viewing hole in the morning.
johnmyster
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My point with the chart is that solubility at reasonable temperatures is much higher than nominal ~32% conc. The fear of developing a salt lick of solidified solute inside your tank seems unreasonable.
There is a reason DEF tanks have heaters and EPA gives a certain time (an hour?) to bring those systems online. Just because overnight temperatures dip below -10C for a few hours doesn't mean the tank will be solid.
Personally, I buy DEF at a convenient pump across from my office. I have yet to deal with one of those jugs since owning the truck. 5 gallons (>2500 miles) is plenty to ensure that I don't need to buy when on our RV trips. Even with our 50 gal titan, it's unlikely that I'll do more than a few fillups without seeing a truck stop with DEF at the pump. More capacity is always better especially if the newer trucks depend more on SCR and less on EGR, which would be a welcome change and imply better efficiency/power related to allowing higher in-cylinder temperatures.
There is a reason DEF tanks have heaters and EPA gives a certain time (an hour?) to bring those systems online. Just because overnight temperatures dip below -10C for a few hours doesn't mean the tank will be solid.
Personally, I buy DEF at a convenient pump across from my office. I have yet to deal with one of those jugs since owning the truck. 5 gallons (>2500 miles) is plenty to ensure that I don't need to buy when on our RV trips. Even with our 50 gal titan, it's unlikely that I'll do more than a few fillups without seeing a truck stop with DEF at the pump. More capacity is always better especially if the newer trucks depend more on SCR and less on EGR, which would be a welcome change and imply better efficiency/power related to allowing higher in-cylinder temperatures.
Great White North Eh
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Ya I ain’t no Chemist but Methanol burns really nice and already exists in the market. But noo they invent a whole new industry that in box form is terrible for the environment and the product doesn’t work well for a thirdish of the world! But hey it’s making whoever owns the chem companies rich so there is that I guess. Rant over fuel-on.