Def usage

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Mar 23, 2021 | 01:48 AM

KCRebel

Thread Starter

Laughing Gas

Joined: Aug 2017

Posts: 799

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From: Tupelo, MS

Def usage

21 450 used a full tank of def in 3100 miles. 200 of those miles were towing with the other daily driving not under any load. My 18 250 would go around 10k on a tank of def with no towing, 5k towing. I haven't checked mine yet but others are reporting a tank of def is used every 1500-1700 miles towing.
Is this considered normal? Never thought I would need a transfer tank for def....

Mar 23, 2021 | 05:11 AM

senix

Super Moderator

Joined: Aug 2008

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From: Frederick, MD

I used a tank every 3K miles with towing a lot.

Are you sure it was full when purchased?

Mar 23, 2021 | 08:54 AM

MadMaxx84

Mountain Pass

Joined: Apr 2020

Posts: 189

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From: Long Island, NY

IIRC, it's been discovered that the '20+ Trucks use significantly more DEF than '19 and earlier.

Mar 23, 2021 | 09:16 AM

B-737

More Turbo

Joined: Dec 2020

Posts: 598

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From: New Jersey

I’m at 3,000 miles and not even used a half tank of DEF. mixed towing probably 50%

Mar 23, 2021 | 09:31 AM

senix

Super Moderator

Joined: Aug 2008

Posts: 37,375

Likes: 1,860

From: Frederick, MD

Quote:

Originally Posted by B-737

I’m at 3,000 miles and not even used a half tank of DEF. mixed towing probably 50%

Towing heavy or light...you have a 2020 or a 2019 or earlier?

Mar 23, 2021 | 09:32 AM

JESTERxHEAD

Senior User

Joined: Jun 2011

Posts: 383

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That's on par with my 2020 F-450. ~500-750 mpg.

Mar 23, 2021 | 09:45 AM

4by4ord

More Turbo

Joined: Dec 2018

Posts: 669

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I'm at 2800 kms with my '21 and my DEF gauge says 7/8 full. The range indicator says I can go another 10,000 km (6200 miles). About 1200 km was heavy towing.

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Mar 23, 2021 | 10:37 AM

KCRebel

Thread Starter

Laughing Gas

Joined: Aug 2017

Posts: 799

Likes: 196

From: Tupelo, MS

Quote:

Originally Posted by senix

I used a tank every 3K miles with towing a lot.

Are you sure it was full when purchased?

Positive it was full upon delivery. Here’s a screenshot that shows the def range. Again this is 90% unloaded miles on the clock at that point.

Mar 23, 2021 | 10:40 AM

#10

KCRebel

Thread Starter

Laughing Gas

Joined: Aug 2017

Posts: 799

Likes: 196

From: Tupelo, MS

Quote:

Originally Posted by MadMaxx84

IIRC, it's been discovered that the '20+ Trucks use significantly more DEF than '19 and earlier.

I’ve read a bit about that as well. One mention of an ecm flash to correct it. Can’t confirm if that helped or not. Makes zero sense. Hoping to figure out a solution or it may fall off.