Acceptable DEF

[JohnH12]

I wasn't sure about which forum this should go in so I figured this one is read by the most folks.
I just got a refractometer to measure the DEF in my RV.
[URL="https://www.amazon.com/gp/product/B073Q2LSG9/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1"]
I know that perfect DEF is 32.5% Urea. The refractometer I have shows a scale from 32 ~ 35.
If 32.5% is perfection what is the acceptable range?
IO have a 2018 Tiffin RED 33AA with a 360 Cummins engine.

[Ljwt330]

Originally Posted by JohnH12

I wasn't sure about which forum this should go in so I figured this one is read by the most folks.
I just got a refractometer to measure the DEF in my RV.
[URL="https://www.amazon.com/gp/product/B073Q2LSG9/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1"]
I know that perfect DEF is 32.5% Urea. The refractometer I have shows a scale from 32 ~ 35.
If 32.5% is perfection what is the acceptable range?
IO have a 2018 Tiffin RED 33AA with a 360 Cummins engine.

Concentration must be 32.5% +/- 0.7%.


That means a low of 31.8% or a high of 33.2%.


How far beyond those limits before sensors respond or poor performance/failure begin is unknown, but the 32.5% concentration is what the CAT is calibrated to for most efficient NOx reduction and dosing.

[Piros1]

FYI from what I have read and been told DEF has a fairly short shelf life, less than a year. Don’t fill your DEF tank at the end of a trip unless you know you are headed out again soon. My coach set for a year between trips and I made that mistake on my way back home. And ended up pumping it out before the next trip and refilled with fresh fluid. Obviously you don’t want to run it out and I recommend keeping no less than a 1/4 tank. It is also recommended that you do jot store your spare jugs of fluid in the sunlight or in freezing temps. It is mostly water and will freeze, mot sure what that will hurt other than it will be a mess. Your DEF tank has a heater built in and your system is designed to pump the DEF back into the tank when you turn your engine off.

[UTTransplant]

A refractometer is only needed if you don’t travel frequently. If you buy from a truck stop with their fresh DEF, you should have at least 12 months andprobably 18 months of idleness before you need to worry. And why have a motorhome on wheels that never turn? Being stationary for long terms is hard on a lot more than DEF.

[JohnH12]

Originally Posted by UTTransplant

A refractometer is only needed if you don’t travel frequently. If you buy from a truck stop with their fresh DEF, you should have at least 12 months andprobably 18 months of idleness before you need to worry. And why have a motorhome on wheels that never turn? Being stationary for long terms is hard on a lot more than DEF.

That's exactly why I bought it. Recent family health issues have had a negative impact on our travels.
I understand that I may have to empty and refill the DEF tank at some point but I don't want to waste the money if the quality is still functional.

[fottip]

Originally Posted by Piros1

FYI from what I have read and been told DEF has a fairly short shelf life, less than a year.

That may be true in the literature. But given the deplorable state of affairs WRT the COVID "crisis", and the stasis it's entailed, a lot of DEF has been in tanks for a while.


Our DEF tank read about 32.3 on the refractometer, and I'm hoping it won't become a problem.