How long does DEF last?

[llscott]

In my 2015 Forester MBS my DEF light comes on about 3100 to 3500 miles of travel....add 2.5 gal and I'm back on the road.
I don't carry that extra weight and just add when my light comes on. Have never found that it was not available in quick order at a wallmart or auto store or service station that sells diesel....price may vary but still not that expensive.

[usraptor]

Originally Posted by 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.

On my '11 Chev, a message on the DIC comes on and stays on until I clear it. And then it keeps reminding me if I don't top off the DEF.

[lacamastraveler]

Originally Posted by bob5560g

The MBS DEF tank holds 4.7 gallons

Some do some don't

[jkoenig24]

DEF has a shelf life of two years. When I had a 2010, 3500 series MB Sprinter, I always got just over 9,000 miles starting from a full tank of DEF. When you get SERIOUSLY low on DEF, a warning light will come on and, you'll get a "countdown". That countdown starts at 20. That number indicates how many more engine starts you'll get before the engine goes into "emergency mode" (meaning engine performance will only allow you to creep along). Once the countdown kicks in, you should still have plenty of time to find and add some DEF. Once DEF is added, the warning system resets.

[wire1946]

It's about 1000 miles per gallion

[TARVIDSON]

It is my understanding on Sprinters that you can get into a shutdown problem adding a little bit of DEF at a time, that it is better to just wait for the light to come on and then fill the tank. That is 5-6K miles on mine, I wish the tank would hold about a qt more as a 2 1/2 gal jug is just a little too much and the stuff should be washed off if it gets on anything under the hood so don't overfill, it foams and creates a hard crust if it is spilled.

[halbright]

I have a 2016 Solera 24W MBS. On a trip of about 6700 miles, I got a bit over 1900 mpg of DEF. When the warning light comes on, you have 1.5 gallons in the tank. You should not have to worry about carrying extra DEF.

[talley]

Just returned from towing trailer 2500 miles to Arizona and back. Started with a full tank of DEF and added 5 gallons on the trip. Price ranged from $11 at Walmart to $22 at a gas stop for a 2 1/2 gallon box. Decided I will always carry a 2 1/2 gallon box in the truck bed.

[grumpyoldman]

No need to carry extra with you. It is available everywhere. The warning light/alarm gives you plenty of time to fill the tank before it runs out. DEF usage is based on fuel used and not miles driven. My DEF usage over the past 3 years is 1.4% of fuel used. That puts me at 5 gallons of DEF per 360 gallons of fuel used.

[SidecarFlip]

One less thing for me to be concerned with. I don't use any and don't plan to. I'm pre Tier 4. No cat pee in my truck.

[dukeboone]

I know it's been said, but I think it's worth repeating... Your DEF tank size will vary based upon the chassis model year. I refilled my DEF after the light came on at 6833mi. Added 2.5 gallons and the light went off. There's a lot of debate (like all things RV) on whether to refill upon the DEF light illuminating, or add DEF incrementally.

[rlschurman]

Have a2015 ram I get about 700 mpg of def. I get more mpg wo pulling my TT

[myclmac]

Planning a long trip, top off before you go. Our MBZ 2401R gauge gives plenty of warning. Buy a fresh box at your next fill up or at the pump at a truck stop. 2.5 gal box fills tank once the light comes on.

[Beachsailor]

We put 7000 miles on our 2016 2401w before we addd DEF. But talking to the MB tech at our MB dealership he recommended that we don't let it get past 1/3 tank before refill. He also explained that the way the sensors work you need to make sure you refill to full when you add DEF. He explained the the counter only resets when the tank is at full and driving the tank down to close to empty can do damage to the DEF storage heater.

[Homebrew]

Originally Posted by 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.

My 2014 Ram came with a gauge in the dash. The truck hold 5 gallons of DEF . We purchase 5-8 boxes when on sale at Walmart for the summer and always carry one box in the back of the truck.

[eyeguy1]

Homebrew what kind of TT do you tow. I also have a 2014 Ram Ecodiesel and are heading out next week for Florida from Southern Indiana

Never mind. I see you have the big boy. Lol

[Homebrew]

Originally Posted by eyeguy1

Homebrew what kind of TT do you tow. I also have a 2014 Ram Ecodiesel and are heading out next week for Florida from Southern Indiana

Never mind. I see you have the big boy. Lol

It's the smallest of the XLR Thunderbolt series .

[eyeguy1]

Originally Posted by Homebrew

It's the smallest of the XLR Thunderbolt series .

Yeah. It I saw on your profile that you tow with the 3500. I have the baby diesel. Lol. I was wondering if you have towed through the Montealgle pass through Chattanooga TN

[halbright]

Why all of the non-MBS responses on the MBS site? Your DEF tanks will be different and your consumption will be different. Let's stick to the category.

[BamaBob]

Originally Posted by 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

Gotta LOVE RV Dealer Information

According to Cummins, If stored between 10 and 90 deg F, shelf life will be 2 Years.

Even if stored at a higher or lower temperature or longer than 2 years, DEF will not go bad. It will lose some effectiveness, and the SCR will dose at a higher rate, but it won't “go bad."