Tip Buying DEF from pump

[lostinfla]

I usually buy my DEF at the pump when filling with fuel just for the convenience of not having to deal with jugs and overfilling. On our last trip, our first stop was near Ocala Fl, so I stopped before the campground to fill up. (I make it a habit to arrive at a campsite with a close to full tank). Stopped at a Loves, got fuel and DEF. While filling the DEF tank, it smelled much like an overfilled cat litter box, but I didn't think much about it. A short time after, the check engine light came on (just orange outline) with code SPN 3216/FMI 2 which translates to "Difference between the expected NOx ppm and the actual NOx ppm is greater than 200 ppm." I ended up syphoning all out of the tank and refilling with Blue Platinum from Walmart. I'm sure if we had a newer coach with the "improved" DEF head, we would have been dead in the water at that point. After running to our next camp (about 250 miles) the light went out with no ill effects. Don't assume the stuff coming out of the pump is fresh. I will NEVER buy DEF at the pump again and I'll check the date codes on the jug to make sure it's fresh.

 

[Neal]

Did you reach out to the station to report it?

Seems like there is risk either way, unfortunate we need to deal with this stuff!

 

[lostinfla]

No. It was Sunday and didn't think they would do anything anyway. You know, that would cost them $$.

 

[Joe doggs]

Back when def heads were in short supply,from Amazon I bought a device,think it’s called a refractometer….smear a little def on the lens,point to light,and it will give you the urea reading,basically tell you if the def is o.k. or not…..even today,when replacement heads are readily available might make sense to always test before filling,and if there is a vinegar/amonia smell I think that usually means the def has gone bad…….great reminder,thank you!!!

 

[Neal]

I own and carry a refractometer, never used it, probably should. I'm still on the truck stop DEF train but we've heard of stories every which way. Unfortunate we have to use this DEF stuff! I guess if we are going to be diligent, no matter the source, we should test it. Fortunately I rarely need DEF so it's not that hard for me, i.e. no excuse.

Amazon product ASIN B073Q2LSG9

 

[Underboss]

DEF is made with urea so it will smell like cat piss. I have done both and prefer truck stop DEF, its the freshest you will find. I wonder if they were getting a delivery as you were filling

 

[flyboy013]

I almost alway buy from Walmart. I test each jug with a refractometer. Never found a bad jug. I visit Walmart often enough while traveling so it’s convenient. Due to the DEF tank being located at the rear of the bus, I don’t like to fill it when fueling.

 

[Rich W.]

You're probably tired of hearing me say it but I never use pump DEF in my coach. To many reasons not to and its of no benefit to me to fill at a truck stop - it takes longer, I’d have to move the coach since the DEF fill spout is 30’ from the fuel fill, and with jugs I can fill at my leisure when stopped anyway. And since I get around 300mpg on DEF its pretty easy to plan ahead, buy enough fresh DEF for a trip and not over buy.

Also for pre-2016 emissions, which includes many 2016 coaches, it is better to keep the tank above 1/2 to keep the mechanical float wet and prevent DEF muck from crystalizing on it and making it stick causing error codes and possible derate (see the TSB below).

So I start full, drive til its down to 3/4, then fill at the next CG. It always will take 2.5 gals at that point so no waste or mess. Also I don’t buy into the “premium” DEF claims about additives, but neither do I use the cheapest stuff. And of course I verify the date codes, consider how it was stored, and if in doubt use my refractometer, which is a rare occurrence these days.

But I had two DEF related issues ending in derate shortly after I bought the coach (in my emissions rookie days) shortly after buying pump DEF. So no more. Its fine in my F250 6.7 but the Freightliner system seems to be too fragile. Or maybe its a coincidence or my imagination, but I’ve never had any issues with jug DEF.

The TSB for pre-2016 emissions: (provides the possibility of a roadside or campsite fix to avoid unnecessary shop repairs) https://static.nhtsa.gov/odi/tsbs/2013/MC-10142383-9999.pdf

I also filled in the wasted space around my DEF tank and added a dump hose box on one side and enough space for plenty of DEF on the other, and of course another compartment light and 120v outlet. Before and after shots:

OE config just screaming for better use of space.

the light was probably overkill but its what I had on hand. Also nice getting the stinky hose out of my clean wet bay.

note my refractometer handily mounted with VHB tape to the top of the tank. Now I need some gasket material to seal the door - gets dirty in there.

 

[Rich W.]

DEF is made with urea so it will smell like cat piss. I have done both and prefer truck stop DEF, its the freshest you will find. I wonder if they were getting a delivery as you were filling

It will always smell of ammonia but if its so strong it burns your nostrils to smell check it, its been exposed to too much heat for too long, the urea is breaking down, and it should be dumped. Ammonia is corrosive and damages things like the sensitive electronics in DEF headers. Not worth the risk.

 

[lostinfla]

Thanks for the idea of adding a floor to the DEF bin Rich!

 

[Neal]

You're probably tired of hearing me say it but I never use pump DEF in my coach. To many reasons not to and its of no benefit to me to fill at a truck stop - it takes longer, I’d have to move the coach since the DEF fill spout is 30’ from the fuel fill, and with jugs I can fill at my leisure when stopped anyway. And since I get around 300mpg on DEF its pretty easy to plan ahead, buy enough fresh DEF for a trip and not over buy.

Yes, you have to pull forward which is not a big deal to me. Pump diesel, which I leave the engine running, pull forward, pump DEF. It's all a matter of personal pref but if you don't trust pump DEF do you trust pump Diesel? Why any difference? Just like any fuel or DEF for that matter, I'm sure it has regulations that govern the filtering, storage, etc. If they offered box Diesel would you use that instead?

I personally think the box vs pump is overblown but it doesn't matter. Everyone does what they want to do. We can all nay say either way. We just hope whatever we are getting from whatever source is quality and not going to cause us any problems. My guess and only a guess is a lot more consumers are using pump DEF (i.e. truckers) than boxed products so if there is going to be a problem it's going to affect a lot more. It sucks either way. These RV myths are always interesting to read, just like the always keep DEF full (which I also don't do, what's the net age of your DEF after 5 years?) vs. cycle it at 1/4 to 1/2 DEF levels as I do. Again, do what you want in the end.

In @lostinfla's case, it sucks, whatever happened or if the DEF was contaminated. Bad deal!

Moral is: I have to trust the fuel coming out of the pump for my car. I have to trust the fuel coming out of the pump for my plane. Why does this change for RV with diesel or DEF?

 

[Rich W.]

Just a couple comments on that: Diesel is a lot more stable and diesel engines have very good on-board filtration compared to DEF, but you still have to be careful and I wont fill up if a fuel truck is dumping a load at the time. Bad fuel can still leave you stranded but its much less common and I carry spare filters just in case. I also carry a spare DEF filter. But the main thing about box DEF is its more controllable and verifiable than pump DEF which is important (to me) since these emissions systems have proven to be so fragile. All it took was a couple ruined trips for me. It may or may not make a difference for the most part, but it is something I can do to have a little more control over the situation, and I also prefer dumping a jug in every few days at my leisure - that part is just preference.

I don't know what the primary rationale is for keeping the DEF tank full or if its even a prevailing concern. For pre 2016 systems it makes sense to keep the mechanical float in the tank from gumming up. For 2016 and later systems, I can’t see how it would matter. But if I rotate 7 - 10 gallons of DEF through my tank on a given trip, the DEF is staying fresh enough given a shelf life of up to a year in 70° - 80° temps. If the tank sat full over a summer at 100° temps, I’d dump it and put in fresh, but keeping it full would still protect the float, and false “low DEF” signals have been responsible for many if not most of the pre-2016 system DEF header failures (hence the TSB I often post).

I don’t operate on trust or myths - I verify as much as possible and take control of whatever I can. I started this DP journey knowing basically nothing about the emissions system and it left me stranded twice on important trips, had me scratching my head quite a few times before I figured it out. I was a trial and error experience with shops trying to charge me for parts and service I didn’t need and repairs that we covered by the emissions warranty.

As I progressed through this learning experience I often read accounts of people spending thousands of dollars to either correct avoidable problems, for repairs that were actually covered under the emissions warranty, or for completely unnecessary work. Its happening as we speak and I have decided to do everything I can to prevent it from happening to me so I can enjoy my coach and make my own decisions on where I spend my money. Ruined trips and inflated and unnecessary repair bills are not good for my vacation and leisure effort. I also study problems that others have had to prevent experiencing them myself, and I try to share what I’ve learned in hopes it helps some folks. Sometimes it does, and sometimes it doesn’t.

Ok that was more than a couple….

 

[Rich W.]

Also for comparisons sake, diesel, gasoline, av-gas, jet fuel, etc have been around a long time and the systems that use them have been perfected over many years. Putting scrubbers in vehicles is a relatively new concept and it was mandated far before the systems were close to being ready, much less perfected, and with no regard for causing drivers to be stranded, wether in personal or commercial vehicles. In fact intentionally stranding the vehicle is one of the parameters built in to the systems, even in public transportation including school busses, and it wasn’t until 2013 that exemptions were developed for emergency vehicles and harvesting equipment. But obviously the systems were faulty and problematic since these exemptions were needed. Even now, 13 years later, the technology hasn’t been perfected but it is a lot better and for the most part, the problems are subsiding in newer vehicles. But you would never see this kind of reckless disregard for operability or safety in the aircraft industry where everything is fully tested before being implemented, and aided by redundant systems. Unfortunately that same level of regard or concern has been withheld from those of us who operate on the ground.

 

[lostinfla]

I should also say that in the 8 years or so of DP ownership after many gasoline powered rigs, I always bought DEF at the pump and never had an issue, but, once is enough for me. If I can take any steps to avoid problems while on the road, I'll not step, but run in that direction.

 

[Neal]

I should also say that in the 8 years or so of DP ownership after many gasoline powered rigs, I always bought DEF at the pump and never had an issue, but, once is enough for me. If I can take any steps to avoid problems while on the road, I'll not step, but run in that direction.

I just hope what you experienced is not a red herring and in fact was the DEF. But it could be a sign that something is wrong and keep close attention, have that DEF head simulator if you don't have one, etc.