How long does DEF last?

[High Desert]

I am trying to figure out how long DEF will last on trips with my 2017 MBS Sunseeker. I have read about different consumption rates, while driving of 1% and up. As I am planning a trip of about 3K miles soon, trying to determine if I should carry a 2.5 gallon container or just plan on topping off at diesel stations along the way? I have had many diesels but this is my first using DEF, so I am unfamiliar with the process. What have your experiences been or what are some recommendations??

[W5CI]

MY 2015 RAM 1 ton diesel uses about 2.5 gal per 1000 miles towing my Cedar Creek

[doc73]

While not a mbs, I get about an oil change out of 6 gallons (7k or so miles ) . There is a percent fluid used per mile driven. I always carry a 2.5 jug just in case I am off the beaten path an cannot get it. Rather safe than sorry.

Edit, truck stops may have it at the pump, more are. But most normal gas stations do not have it either at all or will sell the same jug for 5x to price.

[wanderingbob]

Def is available everywhere , even in the boondocks . Wal-marts , Tractor supply , Home Depot , auto parts store . No need to carry any . My Ram will go 2,500 to 3,500 miles on 2 1/2 gallons .

[BandJCarm]

I dunno. I've got 13,000 after 1st year of this truck, and I guess I've filled up about 4 times........?? Memory is bad.

Every Walmart has it. And I'm sure your vehicle does what mine does, and tell you when it hits about 30%, or somehow lets you know in advance to add some. And almost every truck stop has it at the pump.

DEF fluid has a date code on each box. You're not supposed to mix the batches with different dates, but I quit worrying about that long ago. But if you care, here's some info from another web site, as an example. No clue why they can't just put the simple date, but they don't:

The most important part of the batch code is the third through seventh numbers. There are always going to be two letters or numbers at the beginning of the code, which is the blending facility code, The third and fourth number of the code is the year +1. The fifth, sixth and seventh numbers of the code are the days left in the year, or reverse Julian date."

The date code on a recent BlueDEF box I purchased was GA153590089.Lets break this down into 4 groups of numbers:

GA: The designator of the plant that manufactured the DEF.

15: The year of manufacture plus 1, so this DEF was made in 2014.

359: 365-359 = 6, so the 6th day of the year, or January 6th.

0089: The batch code.

So this container of DEF was made January 6th, 2014.

Specification life for DEF is 2 years at 75F or so. Stored properly, this DEF is good thru January 6th, 2016.Storage life is highly dependent on temperature. DEF stored at 85F only lasts 12 months. Storage above 95F (not unusual in an vehicle parked in the sun during the summer) is limited to 1 month or so.

I worry more about degradation due to heat in the back of my truck (covered with a Retrax), so I don't carry extra anymore. Just add it at truck stops if I need it. Other than the stupid place they put the spout on a GMC, it's been a non-issue for me. Just a few seconds every once in a while.

[SidecarFlip]

DEF consumption is based on injection rates determined by your ECM for optimal conversion in the catalyist so consumption cannot be determined because it varies by miles run, throttle position and other factors.

Lets just say it don't inject very much.

[JLeising]

On our 2012 MBS Solera, we use about one gallon of DEF every 1900 +\- miles. Ours has the "small" tank filled from under the hood. I understand Mercedes also supplies Sprinters with other tank sizes. On ours, the warning light comes on at about 4200 miles, at which point the tank takes about 2 1/4 gallons (a little less than the "typical" 2 1/2 gallon jug). As the warning light is "stubborn" about resetting (can take a couple of restarts, waiting each time for the dash indicators to turn off before cranking the engine) I carry a couple of one gallon jugs with me and try to add one after about 3000 miles, then one every 1800 to 2000 miles - never letting it get to the warning light trigger. I understand newer Sprinters have a DEF level guage available on the dash display (see your owner's manual on how to access).

[Rich.M]

Originally Posted by JLeising

On our 2012 MBS Solera, we use about one gallon of DEF every 1900 +\- miles. Ours has the "small" tank filled from under the hood. I understand Mercedes also supplies Sprinters with other tank sizes. On ours, the warning light comes on at about 4200 miles, at which point the tank takes about 2 1/4 gallons (a little less than the "typical" 2 1/2 gallon jug). As the warning light is "stubborn" about resetting (can take a couple of restarts, waiting each time for the dash indicators to turn off before cranking the engine) I carry a couple of one gallon jugs with me and try to add one after about 3000 miles, then one every 1800 to 2000 miles - never letting it get to the warning light trigger. I understand newer Sprinters have a DEF level guage available on the dash display (see your owner's manual on how to access).

X2

[chroniekon]

We just drove our new Isata 3 from Michigan to Oregon with a loop down into southern Utah, about 3500 miles on the odometer now. The gauge reads about 1/2 full.

[ckabrahamson]

My coach goes through about 1 gal of DEF per every 100 gallons of fuel.

In my experience, DEF is available everywhere, but the price varies greatly. The boxed DEF is convenient, but very expensive. Unfortunately, the hose that is packed with the boxed DEF is not long enough to reach my tank. Also, my DEF tank is on the passenger side of the rig, and the commercial DEF pumps are on the drivers...

My solution - I carry a 5 gallon plastic dispenser in the basement of the coach filled with DEF from the truck pumps (<$3/gallon). I fit a vinyl hose over the spigot, and run it to the DEF tank. I can refill the container whenever I buy fuel, and fill it when needed.

[jamesarnold]

Interesting about the "small tank." I also have a Solera 24S, but my DEF tank is on the right side of the chassis. Once I get the light I put in 2 1/2 gallons and the light goes out within the first mile. Good to go for at least another 4000 miles.

[Claude002]

1 thing to remember if you want to buy bulk, its only 100% good for 6 months only, info given to me by my dealer

[usraptor]

We towed our 40ft 5th wheel from Utah to NY and back with an '11 Chev Duramax and I never had to add any DEF. 'Course I topped it off before we left. I agree, unless you are maybe going out of the country, no need to carry any. It's available everywhere and Wally world generally has the best prices unless an auto parts store has it on sale. And like previously stated, if you are running low the DIC gives you plenty of warning to find a place that sells it.

[Jetjockey6]

I get about 1000 miles per 5 gallons of DEF. A professional truck driver told me
not to buy it at truck stops. Walmart has the best price for a box of it, sometimes as low as $5.99/box.

Jim W

[donanddona]

I would like to share a thought. My 2015 F250 Super Duty uses DEF of course. It is my first diesel. The mileage and time requirements should be a concern as it is a mandate to use. So why not have a gauge or accessible LED readout from the dash for current level? Additionally when starting the regen cycle mode or 1st low DEF lovel (500 mile to power down), I only receive a flash on the dash. It should stay on until manually, acknowledged. Regen and 1st Low DEF alarm (500miles) is determined by speed and therefore varies in time/length. Maybe something like a low tire pressure alarm, It stays on till you press the OK button.

[lacamastraveler]

Many answers here because engine size, load, type of driving etc. all impacts usage. With my 2015 MB I use a gallon approximately every 1,400 miles. I fill before a long trip, carry a gallon with me and, as others said, it can be purchased at most (all?) auto stores and some Wal-Mart's. Just remember to put the blue cap back on (speaking from experience here). Oh, and it's always a good idea to have a bottle of water close by when filling. The stuff is very corrosive. If you spill some flush it off with the water bottle.

[bob5560g]

The MBS DEF tank holds 4.7 gallons, per the manual. Page 182 of my 2015 MBS owner's manual says that the DEF warning light comes on when it gets down to 1.5 gallons. If you do not add any DEF, a second warning with an engine start counter will come on at 0.8 gallons. The MBS will give you 16 engine starts to go and add some DEF. If you still don't add any, after 16 starts you will be limited to a speed of 5 mph. This is all on page 182 of my 2015 MBS owners manual. On the next page it says that DEF consumption will be about 2,322 miles per gallon of DEF.

The MBS DEF tank is huge at 4.7 gallons. My DEF warning light first came on when the odometer hit 7,800 miles, agreeing with the manual estimate of usage. I now have over 22,000 miles and have found that I use roughly one gallon per 2,500 miles driven. Do the math and this means that when the first warning pops up, you should be able to drive another 1,700 miles more before the 2nd warning pops up.

Like you, I new nothing of this so I bought spare DEF for my cross country trip to bring home my new MBS. But based on the above, it will just get old before you need it. Just drive until the light comes on, and then add a jug.

[bob5560g]

Dear JetJockey6,

You said 5 gallons takes you 1,000 miles. Is this a typo, did you mean 10,000 miles? Five gallons of DEF will get my MBS around 12,5000 miles.

[jtownstumpjumper]

Originally Posted by Jetjockey6

I get about 1000 miles per 5 gallons of DEF. A professional truck driver told me
not to buy it at truck stops. Walmart has the best price for a box of it, sometimes as low as $5.99/box.

Jim W

Same thing happened to me at the Loves Truck Stop in my hometown....truck driver caught me refilling two of the DEF 2 1/2 containers that I had previously bought at either WalMart or Sams....told me I was making a big mistake filling from bulk....It was not a good product and I was headed for trouble if I continued to use it....shelf life is short and if you keep it around too long it begins to crystalize.....it's made from Urea, a fertilize, and when you spill any, which I do often because of the stupid design of the fill spout on my Silverado 3500HD, you'll see the white dried stuff form quickly....always wash down when I finish refilling. Don't know....never had a problem on my 2012 2500 HD when I traded with 70000 miles...Only have 6000 miles on my new 3500HD.....I've heard this story from others about shelf life on bulk.

[kayo]

My 2013 Silverado 3500HD uses about a gallon/1000 miles while towing a 16,000 5th wheel and about a gallon/1500 miles w without the trailer.
Walmart has the best price on their private label DEF . Thefluid is injected into the exhaust, not in the engine