Question DEF testing?

[Joe Hogan]

Does anyone test the DEF in their DP? Or do you just follow a specific routine and hope for the best? Recently I came across someone complaining about their Newmar that they had just purchased from a dealer at a great discount, it was a 'new' left over, 2019 maybe or 2018. Been sitting on a desert dealer lot for who knows how long. They had check engine lights, limp mode etc during their first trip which was in my opinion very long for a newly acquired vehicle without so much as an extensive walk around from what I could gather. Some of the problems sounded like bad DEF which is possible if it sits in the hot sun too long, I hear. Does shelf life of DEF decrease dramatically with heat? I am researching diesel issues as I consider upgrading to a diesel.

 

[Neal]

I do not test DEF but I also deliberately keep it fresh by running it to just below half (2 dots of 4 on my display) and go a bit after I'm down to 2 dots. I only fill DEF from truck stops for the same reason Diesel is preferred at truck stops, turn over and fresh. I don't know if there is a way to drain the tank, i.e. pull some plug from below but like fresh tanks it would be nice to dump it in the case of your scenario above and add fresh def. It could be a doser issue, something clogged up from crystalized DEF, who knows. Something for the chassis vendor to investigate.

 

[FL-JOE]

I sit in SW Florida for anywhere from 4 to 5 months during the winter. I usually get one "exercise" drive in but otherwise 99% of my DEF is sitting in the heat unused. I'm guess that for DEF to age out while actually in the tank it would have to sit for a year or more.

Based on recent experience, now every time I hear of issues with a newer DEF tank causing issues I suspect a faulty DEF header. According to North Trail these DEF headers have been failing more than usual.

 

[NWIP]

During Alaska trip and the need to buy DEF in stores I did test with a refactor I had purchased at the suggestion of someone. Usually in lower 48 I always buy bulk at stations and don’t test.

 

[Rich W.]

I have a refractometer I bought basically as a rule-out and to keep me busy while waiting on an apointment at FL for DEF system work. But I’ve never seen “bad DEF” (below 32.8 whatevers - %?)

As far as shelf life and temp, they say it’s good for a year at 50 degrees, six months at 70, two months at 90 and one month at over 100 degrees (or something close to that - close enough for this discussion).

So yes 1-2 year old DEF living in AZ would be highly suspect. I have a syphon device for emptying the tank and I would definitely dump that stuff.

Also DEF has a shelf life and date code (I know I said this was for another day..) and that code is basically the year minus one followed by a reverse Julian date. So if the code had five digits that look like 20305, the DEF was manufactured around the end of February, 2019. Clear as mud? Google it for a better explanation- it’s worth your time because even in the best conditions the shelf life is about a year.

On bulk vs box purchasing, I’ve been told often that with bulk you run a much higher risk of contamination, and three of my DEF episodes have been after a purchse of bulk DEF, so I wont buy it anymore. I really don’t know if it makes a difference, but it appears so to me, so that’s my new policy. Plenty of truckers buy nothing but bulk so it should be fine, but box DEF is more controllable and predictable.

 

[Neal]

I only buy DEF at truck stops and never boxed. I want fresh and low risk of contamination. Same with diesel, high use stations such as truck stops vs algae risk at town stores.

 

[TJ&LadyDi]

On bulk vs box purchasing, I’ve been told often that with bulk you run a much higher risk of contamination, and three of my DEF episodes have been after a purchse of bulk DEF, so I wont buy it anymore. I really don’t know if it makes a difference, but it appears so to me, so that’s my new policy. Plenty of truckers buy nothing but bulk so it should be fine, but box DEF is more controllable and predictable.

It very much depends on where you buy boxed DEF. There have been (and continue to be) instances where unscrupulous people find an empty DEF jug and box, and refill it with water, then return it for a refund at places like Walmart. After being the recipient of such a "restocked return" that was actually refilled with water, we buy our DEF at the bulk pump. On the rare occasion when I must buy a boxed DEF, I insist on opening the outer carton at the checkout counter and inspecting the seal under the cap, along with the expiration date.

I don't know where you bought contaminated DEF in bulk, but I can't imagine that it was at the diesel island at a truck stop. They go through DEF and diesel quickly and it is usually the freshest available. I won't buy DEF (or diesel) at some little, out-of-the-way station that doesn't do volume business; the turnover isn't fast enough to prevent issues.

TJ

 

[Rich W.]

I dont know that I did buy contaminated DEF - might have been a coincidence. Two of the three were a local card-lock station we use, so maybe low volume, but a lot of local truckers and ciy and county vehicles use it. The other was at a Loves.

It could also have been driving in low temps - three times were in the 20’s or high teens. That shouldn’t matter but it’s another variable to think about. Actually two were on Thanks Giving and one on Christmas day, so I was beginning to suspect holiday travel....The fourth time (last time) was in the 50’s and that turned out to be a pump failure. So maybe not temp or holidays.

And yes, imparitive that you check for sealed containers on box DEF.

What happened when you put water in your DEF tank?

 

[TJ&LadyDi]

What happened when you put water in your DEF tank?

Fortunately, I noticed the missing seal under the cap and did not put it in the DEF tank. I have a DEF refractometer and was able to test and confirm that it was, indeed, water in the container. And, on the rare occasions when I use boxed DEF, I slash the container with a pocket knife to ensure that it isn't used for this scam.

TJ

 

[Neal]

Temps shouldn’t matter as the DEF system has a heater. It’s a good idea to let your DEF tank to get down to 50% then refill. I store my coach with DEF full to minimize crystallization. Even if you do get crystallization once you add more DEF the crystals will dissolve.

 

[NWIP]

I seldom buy DEF in the box but on our trip to Alaska we did a lot, bulk DEF is seldom found in Canada or the Yukon. I bought a refractor prior to leaving lower 48 and used on the trip.