The def tank capacity iS48 gallons for the 2019 Ford F 350 according to the manufacturer. But what exactly is def fluid. Diesel exhaust fluid is a liquid used to reduce the amount of air pollution created by a diesel engine. Specifically, DEF is an aqueous urea solution made witH32.5% urea and 67.5% deionized water. But do You really need to use def fluid in Your truck Diesel exhaust fluid is required for a process called selective catalytic reduction (SCR). SCR works by diverting exhaust gases through a filter and then into a catalyst. There, the gases mix with DEF, which turns hazardous NOx emissions into a harmless mixture of nitrogen and water.
If you go to Ford’s website and look at the online owners manual for a 2019 F350 Diesel it will say the DEF tank is 28L which converts to 7.396 gallons. It also says the the 176” wheelbase Super Duty truck has a 181.7L fuel tank which converts to 48 Gallons. Https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?variantid=6297&languageCode=EN&countryCode=USA&Uid=G2006399&ProcUid=G2006402&userMarket=usa&div=f&vCode=&vFilteringEnabled=False
Fred
August 10, 2021
My owner's manual say 7.4 gal.
Steve S
December 8, 2021
48 gallons is the fuel tank. The DEF tank is around 7. The last time I filled it up I added 6
Looks like some are confusing DEF with diesel fuel, two very different liquids. Do not make the mistake of putting DEF in your fuel or vise versa. Also to answer the question if you really need to use it.... Modern diesel engines will shut done if your DEF tank is empty just as if you were out of fuel, most trucks will get about 800 miles per gallon so it should not be that hard to keep from running out.
Paul Sylvester
May 22, 2023
Whoever thinks the DEF tank on a Ford Superduty is 48 gallons is an idiot. There are some Superduty trucks with a 48 gallon diesel tank but certainly not the DEF tank. Standard fuel tank on a 2022 F350 crew cab short bed diesel is 34 gallons! If you don’t know what you are talking about, don’t answer!
A DAY
December 19, 2022
I JUST CANT BELEIVE THAT SOME PEOPLE ARE THAT STUPID AND CANT JUST READ THE OWNERS MANUEL TO GET SPECS. FOR THE GUY WHO SAYS ITS 48GAL YOUR A IDIOT, THATS THE FUEL TANK NOT THE DEF AND ITS THE TOP ANSWER HAHA. I OWN A F350 48GL DIESEL AND BETWEEN 7-8 GL OF DEF. WITH THE LONG WHEEL BASE. READ TOUR BOOK PEOPLE. FROM A ASE CERTIFIED MECH.
Donald Y
July 16, 2020
The def tank capacity is 48 gallons for the 2019 ford f350 according to the manufacturer.
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