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[TCDiesel]

I won't mention names ,one of the largest commercial Freight companies in NA, wants its drivers to keep DEF tanks Full when convenient. I'm sure they have the Data to back up Why they enforce this Policy. Running Your DEF down to the point it affects the operation of the Truck is considered a Incident.

 

[CoastyAV8R]

So do most keep their DEF tanks full? I've put 16,000 miles on mine since it was new so my concern is DEF "going bad" due to the lack of use.

 

[TFucili]

So, contamination aside, is variation in concentration the only issue with "old" DEF? Can it be sour/stale/etc. and still be proper concentration?

 

[Newsa]

So, contamination aside, is variation in concentration the only issue with "old" DEF? Can it be sour/stale/etc. and still be proper concentration?

I don't think it ever gets sour or stale?

But it (urea) can start prematurely turning into ammonia (also soluble in water like urea). Which would decrease it's potency wheras water evaporating out would increase it's urea concentration.

What I don't know is if the pump/sensor and or injector can be damaged by ammonia?

 

[Wayne M.]

I think this corruption might be picked up on the refractometer. If ammonia has a different specific gravity than urea, it will.

 

[Wayne M.]

Here’s a thread I started a while back regarding DEF testing. I just remembered it. Shows views through the refractometers I still have.

https://www.turbodieselregister.com/threads/testing-def.258485/?p=2507935#post2507935

 

[Newsa]

I think this corruption might be picked up on the refractometer. If ammonia has a different specific gravity than urea, it will.

It will. Ammonia is a gas dissolved in water. Urea is a solid dissolved in water. Ammonia dissolved in water would have nearly the same SG as pure water.

 

[gsbrockman]

CERT DEF producer want to put fear into users. Keep your DEF tank Full year round will produce better results that running down to Empty and adding. Their is so much myths surrounding DEF, I see why owners have issues with its use... and like X% info today found on the social Networks its founded on tainted info.

My experiences have been that running the tank down to the “Low DEF Refill Soon” or “XXX Miles to Derate” messages and filling the tank with bulk DEF netted me no problems on my 2014 RAM 3500 through 362k miles, and likewise has worked well on my 2018 RAM 4500 through 118,964 miles and 271.617 gallons of DEF. Running it almost completely out then refilling with the freshest DEF has to be better than throwing in a gallon or two here or there, similar to a dog marking its territory.

The least amount of DEF I’ve ever put in the 4500 has been 6.829 gallons....the most was 9.252 gallons. Most refills have been in the 8.4 gallon to 8.6 gallon ranges over all.

 

[Wayne M.]

It will. Ammonia is a gas dissolved in water. Urea is a solid dissolved in water. Ammonia dissolved in water would have nearly the same SG as pure water.

If I remember, I think I can get some ammonia cleaner at work. We see the result of 50/50 urea/ water mix in my linked post above. I can test ammonia/ water mix to see what comes up.

 

[TCDiesel]

My experiences have been that running the tank down to the “Low DEF Refill Soon” or “XXX Miles to Derate” messages and filling the tank with bulk DEF netted me no problems on my 2014 RAM 3500 through 362k miles, and likewise has worked well on my 2018 RAM 4500 through 118,964 miles and 271.617 gallons of DEF. Running it almost completely out then refilling with the freshest DEF has to be better than throwing in a gallon or two here or there, similar to a dog marking its territory.

Greg , their are minor benefits to running low and refilling. and since you are consuming DEF daily in your use it really makes No different.

larger quantity of DEF will keep it properties in check.. In winter months owners that run down to 1 Gallon or less when it freezes at night the heater engages how it thaws effects smaller amounts... MB had many problems DEF/Tanks BC of the heating system install in MB DEF Tanks.

Owners that consume DEF at 2+ Gallons or More Monthly can run their Tanks however they like in summer months or temps above 20K.

They is NO down side to keeping DEF tanks full when convenient. it will last years and the bigger the Temp swings the better for DEF in MAX Tank capacity.

 

[Wayne M.]

Big differences between big truck DEF heaters and pick up truck heaters.
Big truck use engine coolant and electricity to keep things warm. Those setups are a bit more robust.

 

[Newsa]

I used to get an error code (NOx out of range) that I thought was aggravated by low def. Bob 4x4 even suggested that my truck was telling me that it needs def. At that point, I just thought maybe my def gauge was working differently than everyone else"s.

But finally, my dealer agreed to install a new NOx sensor and I"m down to half full on the gauge. I think it really only has 1 or 1.5 gallons in it though.

I am relieved I can finally run out the "old" def. I think it is comforting putting in all new fresh. Don't know if it really matters, but sounds like a strategy.

 

[TCDiesel]

They all get hot........ and Many Class III and up are 100% electric.

 

[TCDiesel]

Just for SG next winter for us cold area owners take a container like the one below and when the temp get's below 10F push in the corners so it fills up to the neck, let it freeze solid ONE BIG block, Even the push in corners will still be indented , DEF expands very Little, it will also be crystal clear. Or should be...

 

[pwr2tow]

I only fill my def tank when I'm going to pull a load a couple thousand miles at one time which is once a year. The other towing is local. So once a year I fill the def tank, all the other times I wait until the gauge is between red mark and 1/4, then I just dump in 2 1/2 gallons which brings the gauge up to 3/4. Has worked this way for 3 1/2 years without incident.

I never fill the def tank between October and April. Common sense tells me it's easier and faster to thaw 2 1/2 gallons vs 5.5 gallons at -40*F.