DEF life span and quality considerations

[Neal]

It’s frustrating how much divergent information is circulating on this topic. At FPU, my tech said to keep it at the 75% full level. At the latest AIM rally, a Freightliner rep said to keep it full. I’m going to begin keeping it as full as possible per the FL guy. We’ll see what happens with that.

It is frustrating and we never know who to believe. The tech’s aren’t RVers and I take with a grain of salt the various sources. There was an RVer that was told by a Newmar tech to use the small (3/4” garden hose port) on the end of the sani-con. I tried to explain no, that’s wrong, that is going to give you a lot of backpressure but they believed the tech but eventually changed to the larger port on the end of the sani-con. The same goes with tire pressures, every different shop service worker has their opinions. Even RVSEF (or whoever they’re called) that I paid for corner weights gave me their opinion on tire pressure instead of chart data. I didn’t pay for an opinion on tire pressure, i was not happy! Do we need palm readers next?

Collect the data and opinions, research, make your decisions based on the aggregation of info and who you want to believe. We want to believe some of these techs should know, I’ve learned otherwise.

 

[Joe Hogan]

This thread is very interesting to me in a theoretical sense.
Urea is a dissolved salt and as such will crystallize as water in the solution evaporates. Crystals will go into solution once rehydrated.
However many floats on DEF headers have become stuck as DP sits with half filled DEF tanks due to crystallize urea on moving parts from what I have read.
DEF will freeze and expand by some 7%. Not sure how sensitive the DEF delivery system is to freezing fluid.
Needless to say DEF is a fluid that needs to be managed.
As with most systems in a diesel they “need” to be operational on a regular basis. Fluids consumed regularly.
As we all know, sitting parked in storage is the worst thing for large machines.
Testing urea concentration at the pump is not so convenient nor at the store checkout.
On top of that a very complicated delivery system that is temperamental doesn’t help.

Solutions: in my opinion first step is to understand the system and how to determine issues, next buy DEF from reputable suppliers with care, ( sealed containers or fuel stops with maintained pumps), then regular maintenance from a knowledgeable shop.
And of course fingers crossed things don’t go wrong.?

 

[Neal]

I agree and I think we all operate with paranoia of the DEF crystallization. But if we are given the “recommendation” of letting it go to 2 dots until refilling, then it probably wouldn’t matter to go to 1 dot. Some people run full all the time, FL gives the guidance to go to 2 dots then refill. That’s what I do 99% of the time. On the way home I wanted to go lower to get more “fresh” filled and let it sit on 2 dots (half) for a longer time, wasn’t long enough as it was only just below 1/2 on the tank gauge. For whatever reason my coach uses very little DEF, it is very efficient for whatever reason compared to others. I think if you’re going to let it run down further then carrying a box of DEF would be good practice in case crystallization becomes a problem. But again, at what level does this become a problem? Where are the parts affected? Are they at the top? bottom? 3/4 way down? If they are at the bottom then why would any level matter other than above this point? We all tend to make assumptions on these things and none of us know the real answer without looking at a diagram of the tank and internals to understand where these parts of concern reside.

 

[Neemer]

I’ll buy the house a round when we finally get to a place that DEF header issues are in the rearview mirror. Something else will come along, but hopefully whatever it is doesn’t strand anyone beside the road or kill an entire summer travel season. This mess is is just that: a mess.

 

[Neal]

The topics have converged, this thread really isn’t related to the DEF head issue but it made me decide to voice concerns I’ve had on DEF management and my thoughts on tank level management. I’ve been a “victim” of peer guidance on how low to let DEF go before refilling, I’d like to get to the bottom of it (pun intended).

 

["EZ"]

That statement appears contradictory to me. If shelf life is affected by high temps, then it must also affect quality. Unless quality falls off the edge of the table at the end of shelf life, there has to be a degradation curve. I’m not taking issue with you, EZ, but I’d like to see some real data on this. Two years is a long time. What exactly is the impact? Halved? Worse?

Back in 2010 when I sold my FIRST Ram 3500 with DEF our shop didn't know they were supposed to fill the DEF tank during the PDI. I delivered the truck to the customer and they took it out of town on a job the next day. The DEF light came on so they stopped at a parts store 100 miles away and bought a couple jugs of DEF that was sitting in the front window on display (remember, this was all brand new technology). They got about 10 miles away and the truck shut down. We had to tow it from Knoxville TN back to Chattanooga TN to fix it in our shop because it was brand new and only had 110 miles on it! Turns out the DEF fluid they put in it was bad. The short time it had sat in the window of the parts store in the full sun was enough to kill the DEF fluids shelf life. Hard expensive lesson learned. DO NOT let your DEF sit in the heat any longer than you have to. Store it in a cool dry place, or you too may have to be towed................

 

["EZ"]

The DEF tank has a heater. Not sure what temp it heats to.

It keeps it from freezing.

 

[Neal]

Back in 2010 when I sold my FIRST Ram 3500 with DEF our shop didn't know they were supposed to fill the DEF tank during the PDI. I delivered the truck to the customer and they took it out of town on a job the next day. The DEF light came on so they stopped at a parts store 100 miles away and bought a couple jugs of DEF that was sitting in the front window on display (remember, this was all brand new technology). They got about 10 miles away and the truck shut down. We had to tow it from Knoxville TN back to Chattanooga TN to fix it in our shop because it was brand new and only had 110 miles on it! Turns out the DEF fluid they put in it was bad. The short time it had sat in the window of the parts store in the full sun was enough to kill the DEF fluids shelf life. Hard expensive lesson learned. DO NOT let your DEF sit in the heat any longer than you have to. Store it in a cool dry place, or you too may have to be towed................

I'll continue to use truck stop DEF over boxed DEF. It's underground and not in sunlight, it's constant temp (56 degrees I believe), or at least some cool consistent environment, and there's turnover. If it was bad a lot of customers would be affected, same with the diesel coming out of the pump, a situation any station cannot have happen. Boxed DEF has too many unknowns, I'll avoid it unless emergency use.

 

["EZ"]

I'll continue to use truck stop DEF over boxed DEF. It's underground and not in sunlight, it's constant temp (56 degrees I believe), or at least some cool consistent environment, and there's turnover. If it was bad a lot of customers would be affected, same with the diesel coming out of the pump, a situation any station cannot have happen. Boxed DEF has too many unknowns, I'll avoid it unless emergency use.

Smart plan Neal.

 

[FL-JOE]

I think Neal summed it up pretty good, no matter if you are in a large DP or a 1-ton PU truck with DEF. Use the freshest product you can, which will generally be bulk from major truck stops, and try to manage your levels according to your usage. In other words, don't sit in the Florida Keys for 8 months with a full tank of DEF.