OLD DEF??

[TS21sso]

Recently, going from a 5th wheel to a used DP I have a question about the age and effectiveness of DEF that is in the tank of a little used motorhome over the past year. As a driver of a Diesel pickup, of course I add fresh DEF on a regular basis. The question I have for the DP owner is; What has been your experience with the DEF when your unit has been in storage for lengthy peroids, especially during warmer months when we know heat effects the DEF?

[NRALIFR]

Buy a DEF refractometer on Amazon for less than $20 and you will know if it’s good or not.

:):)

[SidecarFlip]

I've never understood why Urea and deiuonized water has a shelf life. Nothing there to degrade.

[Trumpet_Player]

Cummins Filtration has published a very good article on DEF. They state that the shelf life of DEF when stored at the temperature specifications published, shelf life of DEF will be two years. The statement from Cummins is as follows:

Q. What is the shelf life of DEF?
A. The shelf life of DEF is a function of ambient storage temperature. DEF will degrade over time
depending on temperature and exposure to sun light. Expectations for shelf life as defined by ISO Spec
22241-3 are the minimum expectations for shelf life when stored at constant temperatures. If stored
between 10 and 90 deg F, shelf life will easily be one year. If the maximum temperature does not exceed
approximately 75 deg F for an extended period of time, the shelf life will be two years.

A link to the entire article is here: https://www.cumminsfiltration.com/sites/default/files/MB10033.pdf

[MountainAir05]

Suck it out and put in new when you get ready to drive it. It has a shelf life of 18 months, so you sort of need the jug it came in to know for sure.