Javi's Rules for DEF Usage..
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Senior User
Joined: Aug 2012
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From: Waco, Tx
Javi's Rules for DEF Usage..
Follow these simple rules and DEF will not cause you bad dreams.. 
- If you can't remember the last time you added DEF... pour some in..
- If you're headed out on a trip... Top off the DEF
- If you see the message “Less than 1/2”.. Add DEF
- If you ain't seen the message “Less than 1/2” in a good while.... Add some DEF
- If you ain't added any DEF in the last couple of thousand miles... Add some DEF now.
- If you're at the truck stop filling your truck with diesel and there is a DEF pump right there... Add some DEF to the DEF tank right now..
Cargo Master
Joined: Nov 2005
Posts: 2,051
Likes: 10
From: TEXAS
Follow these simple rules and DEF will not cause you bad dreams..
- If you can't remember the last time you added DEF... pour some in..
- If you're headed out on a trip... Top off the DEF
- If you see the message “Less than 1/2”.. Add DEF
- If you ain't seen the message “Less than 1/2” in a good while.... Add some DEF
- If you ain't added any DEF in the last couple of thousand miles... Add some DEF now.
- If you're at the truck stop filling your truck with diesel and there is a DEF pump right there... Add some DEF to the DEF tank right now..
Hotshot
Joined: Nov 2000
Posts: 11,591
Likes: 14
From: Pflugerville, tx
I use the same, but carry 1 jug. can always buy another
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Post Fiend
Joined: Jun 2004
Posts: 9,293
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From: Parker, CO
Follow these simple rules and DEF will not cause you bad dreams..
- If you can't remember the last time you added DEF... pour some in..
- If you're headed out on a trip... Top off the DEF
- If you see the message “Less than 1/2”.. Add DEF
- If you ain't seen the message “Less than 1/2” in a good while.... Add some DEF
- If you ain't added any DEF in the last couple of thousand miles... Add some DEF now.
- If you're at the truck stop filling your truck with diesel and there is a DEF pump right there... Add some DEF to the DEF tank right now..
Continually topping off the DEF will in some cases lead to the miles to empty continuing to count down regardless of the DEF tank being full. Then you have to take a trip to the nearest Ford dealer to have it reset
Follow what the owner's manual states, and watch the messages on the dash for proper DEF usage.
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Senior User
Joined: Aug 2012
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From: Waco, Tx
Sorry, but this is terrible advice and can actually cause trips to the dealer.
Continually topping off the DEF will in some cases lead to the miles to empty continuing to count down regardless of the DEF tank being full. Then you have to take a trip to the nearest Ford dealer to have it reset
Follow what the owner's manual states, and watch the messages on the dash for proper DEF usage.
Continually topping off the DEF will in some cases lead to the miles to empty continuing to count down regardless of the DEF tank being full. Then you have to take a trip to the nearest Ford dealer to have it reset
Follow what the owner's manual states, and watch the messages on the dash for proper DEF usage.
As far as I can see the owner's manual says nothing about the interval of filling the DEF tank or danger warnings of frequent topping off , IF you have seen such information please post it or a link to the information..
As a note... I've followed my own rules for more than a 100K in each of three trucks and I've never had a single issue with DEF, so I reckon I'll just keep on doing it till you prove me wrong... and you haven't seen me crying on the side of the road out of DEF either..
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Senior User
Joined: Aug 2012
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From: Waco, Tx
Although I see on almost a weekly if not daily basis at least one person who is stranded or worried about being stranded by an empty DEF tank.. Just two weeks ago we were camped at Goose Island SP on the Texas coast and our neighbor came driving up in a rental car... I asked where his truck was ( a '12 F350 SRW) and he replied.. at the dealer... It shut down because I forgot to add DEF... I just hate the stuff..
Not to put it in prospective.. at the turn off the highway into the park is a truck stop/convenience store that sells diesel and DEF... he filled his truck with diesel at that store that morning...
Prolocutor
Joined: Jan 2009
Posts: 13,618
Likes: 1,247
From: Western MA
It's also not the best system because it never lets the old DEF run down. Def goes stale especially with heat. Constantly topping it off contaminates your new, fresh DEF with lots of old stale DEF. Best to run it down before topping it up.
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Senior User
Joined: Aug 2012
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From: Waco, Tx
Let's work on the assumption that I'm not suggesting topping it off every 20 miles.. Okay..
It works on the dilution factor... the tank is 5 gallons... pour a gallon in to fill it and you've diluted the old DEF with new DEF by 1/5th or 20%
2 1/2 gallons to fill would be a dilution factor of 50%...
So with my truck I'm diluting the old DEF with New DEF at a 50% ratio every couple of weeks, I really don't think shelf life come into play here.. or for most of us for that matter. Now if you park your truck for months at a time, especially in weather below freezing then it certainly might come into play.
Another thought occurred to me as I was typing this..
For those of you advocating running the tank dry or nearly dry... what you think about the sediment in the bottom of the tank from the Urea coming out of solution in cold weather... it is after all a solid dissolved into a liquid.
