Top-off DEF or Refill When It's Near Empty? Which is Better

[BUSHRVN]

If you live in a winter freeze zone, I’d only fill to 3/4 full max. Not sure what the JL manual says but the Ram 3500/Cummins manual says 3/4 max in the winter where freezing happens or you can risk busting the tank. Gotta leave room for freezing expansion. I run them quite low so that I’m removing as much of the “old” dated fluid out, then put in fresh fluid. In summer I’ll fill it right up, winter I’ll only go to 3/4 full max. If you’re not going through it very fast I’d recommend not putting too much in so it doesn’t go bad on you before you use it up. But if your off roading and getting some good slopes off road it’s best to be sure it’s quite full or you’ll get low def fluid warnings and other issues.

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[ogo]

I’m intrigued cause when I picked up mine it was right at 3/4 filled of DEF so I have about just over 2K miles on it and I’m at half now on DEF I’m really interested in hearing from more members in regards to driving styles etc as it seems everyone is getting a different consumption on the DEF usage or amount of miles, thanks for sharing!

When I picked up my jeep it probably had about 3/4 tank of DEF but like I said earlier I didn't find the gauge until I was further into my trip.
1400 miles of the almost 2000 miles on my jeep were from my road trip after picking it up and visiting family up in New York...so it was a road trip from Koons in VA to the Utica area in NY before heading across southern NY state towards Lake Erie and then coming back down south to NC. So a lot of highway travel of varying speeds.

Now back in NC, I've taken it down to Uwharrie for a bit of tooling around and other than that it's mostly been around town.

 

[the_jeepeo]

“all the dust and grime on the end of the diesel nozzle. That being said strongly suggest keeping a mechanic rag tucked inside your vehicle. The dirt and grime around your filler cap should be wiped away along with the end of the nozzle at the fueling station before putting it in the filler neck. I know this is all extreme I just don't want it in my fuel system. I have seen some very dirty cake on nozzle ends. In that case I will try and run any residual fuel out the nozzle end by lowering the nozzle to the ground while wiping the outside clean with my mechanic rag, before inserting it in my filler neck. I've even squeezed off a couple ounces onto the ground if I can't get a residual flow. Same at the public drinking fountains, ( Flow 1st, then drink) It's called quality assurance and it does not exist widely or commonly any more at fuel stations.
(one exception, Costco, if they have #2, Does a good job) Otherwise you must do-it-yourself.”

Won’t be needing my mechanics rag at this place! Cleanest nozzle, diesel or gas, that I’ve ever used.

 

[Deke]

I fill only when low and just like my wine, I buy it by the box.

 

[zouch]

in order to try to avoid using old DEF, i generally run mine down and fill it up (or near full) when it's low. the exceptions might be if i expect the possibility of not being close to a source of fresh DEF, and/or to be doing some serious off-camber work.

i've had the Y81 re-flash done; my understanding was that it was likely to make it use more DEF, but i haven't noticed a significant change.
since then i wanted to run it low again to verify that the warnings were working properly after the re-flash, and just got the "will not start in 500 miles" warning once yesterday while showing about 3/16s of a tank on the gauge.

it did seem to use DEF faster when i first got it, but it might just be that i was hyper-sensitive to it then.

FWIW, my fuel tank was full when i bought my J**p at Antioch, and the DEF was very nearly full as well.

 

[smokeythecat]

This is not specific to diesel, but I wonder if this still applies...

https://www.consumerreports.org/cro...y-low-gas-in-the-tank-can-be-costly/index.htm

 

[Paluss]

in order to try to avoid using old DEF, i generally run mine down and fill it up (or near full) when it's low. the exceptions might be if i expect the possibility of not being close to a source of fresh DEF, and/or to be doing some serious off-camber work.

i've had the Y81 re-flash done; my understanding was that it was likely to make it use more DEF, but i haven't noticed a significant change.
since then i wanted to run it low again to verify that the warnings were working properly after the re-flash, and just got the "will not start in 500 miles" warning once yesterday while showing about 3/16s of a tank on the gauge.

it did seem to use DEF faster when i first got it, but it might just be that i was hyper-sensitive to it then.

FWIW, my fuel tank was full when i bought my J**p at Antioch, and the DEF was very nearly full as well.

Thanks for the feedback, still getting up to speed on this, most are reporting a short shelf life for DEF, my searches are indicating a 2 year shelf life for DEF, if so, that seems to be a reasonable shelf-life. Is the issue with ppl trying to store DEF at home? I assume there is an expiration date on the container?

 

[JLeco2022]

i fill up my DEF at truck stops, its way cheaper then the box

 

[Parker]

I'm at 3,800 miles and have just added my second 2.5 gallon refill. I believe my first 2.5 gallon refill was around the 1,800 mark.

RDoug, your DEF usage is just about the same as mine is. I don't do much city driving. Freeway to get out in the countryside, then trail driving.

 

[Deleted member 59498]

I put the blue def box in at little below 1/4 tank, will do it again when it gets down there under a 1/4, hopefully using up the older stuff or at least refreshing it.

 

[GtX]

I put the blue def box in at little below 1/4 tank, will do it again when it gets down there under a 1/4, hopefully using up the older stuff or at least refreshing it.

This has been my strategy too.

 

[Shibadog]

Guys, seriously look at buying your DEF at the pump (where the big rigs get theirs). My last DEF in my Ram was $2.79/gallon. The 2 1/2 gallon jugs around here sell for anywhere from $19-$24. You can significantly cut your costs by getting it from the pump. Plus heaven only knows how long that jug has been on the shelf. At a larger truck stop there is a lot of turnover o your DEF should be at least as fresh if not morose than the jog.

 

[Wrangler man]

Guys, seriously look at buying your DEF at the pump (where the big rigs get theirs). My last DEF in my Ram was $2.79/gallon. The 2 1/2 gallon jugs around here sell for anywhere from $19-$24. You can significantly cut your costs by getting it from the pump. Plus heaven only knows how long that jug has been on the shelf. At a larger truck stop there is a lot of turnover o your DEF should be at least as fresh if not morose than the jog.

Majority of my traveling doesn't assure nor do I want a plan nearby or distant truck stops for my def needs. The 2 1/2 gallon jugs ARE DATED. I store mine in my climate controlled home (as def is temperamental to temperatures) and I live in extreme heat during the summer therefore I avoid filling a quarter tank since my Jeep sits in the garage and is a second driver. Add as needed. I'm also able to load a jug when heading out on an extended outing, or top it off knowing I would be traveling a great distance. Most important to me, I will only use "Blue Platinum" which is the superior "IMO" and others. In addition the crystallization on the end of the nozzle at the station is something I don't want to get into my injection system. Yes you could wipe the outside of the nozzle off but you cannot get inside the nozzle. It's all a little extreme but I've heard how temperamental this whole def injection system is on our Jeeps, therefore I take all the precautions to avoid troubles. One particularly extremely windy day this summer the desert blow sand coated the outside of the diesel pump and nozzle. Knowing sand particulates were most likely inside the tip of the nozzle. I flush the tip and wiped the outside before inserting the nozzle into neck my fuel tank. IMO every little bit of precaution and extra care you take, may and hopefully will prolong, the life of the entire fuel system. Def diesel systems are in no way to our advantage and unfortunately were forced upon us. Remember "kumbaya and green" is not always better. (VOTE SMARTER!) Therefore we're stuck with it, and one (me) might want make the best of it. Merely hoping to extend and assure the life of the diesel fuel system. IMO
Good luck, remember these diesel wranglers will be discontinued next year and I hope we're All ( especially ALL of us "green nozzle guys and gals") waving the thumbs up and the Jeep to each other in the long and distant future.

 

[JL Diesel]

Guys, seriously look at buying your DEF at the pump (where the big rigs get theirs). My last DEF in my Ram was $2.79/gallon. The 2 1/2 gallon jugs around here sell for anywhere from $19-$24. You can significantly cut your costs by getting it from the pump. Plus heaven only knows how long that jug has been on the shelf. At a larger truck stop there is a lot of turnover o your DEF should be at least as fresh if not morose than the jog.

At $20 a jug and I have to add it every 2000 miles that’s a penny a mile. I don’t understand the cost complaint.

 

[Ratbert]

At $20 a jug and I have to add it every 2000 miles that’s a penny a mile. I don’t understand the cost complaint.

If I have the option to pay $7 for something that's most likely better than the $20 item I'll usually opt for the $7 option, especially if I don't have to deal with all of the additional packaging.

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