Community Forums

Tigerfan1 · 10-21-2018, 10:38 PM

Our new to us coach has Def fluid that has been in the Def tank for about a year. The last time the previous owner used the coach was October of 2017. I am in the process of changing all fluids and filters and was wondering if I should drain the tank and fill with new fluid. I have driven the coach about 500 miles with this fluid and the engine has run fine. However, if it can do damage to the emissions system do to age then I will drain and discard. Thanks for your help.

Breezy2006 · 10-21-2018, 10:44 PM

If it has been stored in cooler temps you should be able to get another year off this fluid. If above 85 for a number of days the shelf life starts to decline. There is more data out there. You probably use one gallon per 250-300 miles.

vsheetz · 10-21-2018, 10:52 PM

I would fill it up with fresh and run it. Run it awhile, then top it up again, etc

FLSteve · 10-22-2018, 04:33 AM

Quote:

Originally Posted by vsheetz

I would fill it up with fresh and run it. Run it awhile, then top it up again, etc

I agree with vsheetz … better doing this vs. sitting on the side of the road!

FLSteve

C.Martin · 10-22-2018, 06:35 AM

I almost never "fill" the tank.

We live in South Florida...and heat is an issue. I keep my DEF around 1/4 to 1/3 full, so that I can mix in new DEF occasionally.

IF we're headed out on a longer trip, like the trip out to ABQ last year for the Balloon Fiesta, I'll do a rough calculation to figure out how much to put in based on expected need.

I get roughly 7.6mpg...so I divide my total trip length by that...and that gives me an estimate of how many gallons of diesel I'll use. Then divide that by 53...because that seems to be how many gallons of diesel I burn per gallon of DEF. (Approx. 399 miles/gal on DEF) So, my first stop...I get enough DEF for the whole trip, and don't have to worry about adding later. IF it's a really long trip...I'll add enough to get out there...and then again to get home.

So, if you prefer to manage your DEF...I would favor siphoning out some old DEF, or draining ...vs FILLING on top of it with Fresh. I just cannot use a FULL tank of DEF in a reasonable time period. Many of our trips are short 300 to 600 mile round trip...and it would take me months and months to use a FULL DEF tank.

IF you're heading cross-country...then I would just use what you've got and add fresh after that's been almost depleted.

GlampDaddy · 10-22-2018, 07:38 AM

Quote:

Our new to us coach has Def fluid that has been in the Def tank for about a year. The last time the previous owner used the coach was October of 2017. I am in the process of changing all fluids and filters and was wondering if I should drain the tank and fill with new fluid. I have driven the coach about 500 miles with this fluid and the engine has run fine. However, if it can do damage to the emissions system do to age then I will drain and discard. Thanks for your help.

We bought our Ventana in a private sale in SW Florida. It had been sitting unused for a little more than a year with 3/4 tank of DEF. During the drive back to Texas (1350 miles), I topped off the DEF a couple of times to mix the old with some fresh. We had no problems. The batteries were an entirely different problem...

PanJH · 10-22-2018, 11:46 AM

It looks like you are in Michigan. Cool temps there ( <77 daily average) .... the DEF would be good for a year and a half. You should be good to go and just drive and replenish as needed.
Now, if you are still uncertain, go ahead and drain it out and get some fresh from the pump at Pilot/FJ. I think the tank os 13-14 gallons so at a bit under $3/gal, you'll be out $40.

C.Martin · 10-23-2018, 11:37 AM

https://quickserve.cummins.com/qs3/p...n/4021566.html

Hope that link works...it's from the online Cummins manual.

I tried to find the link again about DEF derates. I read somewhere that if the system detects an incorrect percentage of Urea, it will derate the engine until the DEF is brought back up to standards. Another thing that manual said...which I didn't know...If you stop for fuel...and fill your tank, but the DEF is below a certain percentage of fill...it won't let you start the engine. I guess it's a "Hey Dummy...remember to get DEF too...Mode"... I've never let my DEF get that low.

I would guess in the Northern Tier states...you're DEF is better than mine... We've got plenty of days over 31 degrees C here in Florida.