Forum Discussion

Cougarnewbie's avatar
Cougarnewbie
Explorer
Dec 08, 2020

Stale DEF

Because of Covid my F-350 6.7 diesel has been garage kept since February. The DEF tank is full. DEF has a shelf life. Should I be concerned enough to consider draining the old DEF? My first diesel.
Thanks
AL
  • How hot was the garage? Did you open the door at all during the summer? Hard to believe that you haven't driven the truck at all since Feb.

    Hottest my garage got in August was 100*, but that was up in the rafters. The DEF tank on the truck sits down low, shielded from light and by the truck body, so probably never got hotter than ambient temps in the 80's.

    Your DEF is still not a year old, it's probably fine. You should be driving the truck at least once a week to keep all the seals lubed and the fuel fresh. If you want to burn off some DEF, hook up the trailer and take a quick trip.
  • Afraid to drive because of the Rona?

    Some things are a mystery.
    Almost as confusing as being afraid to camp because of the Rona....

    May as well empty the tank because you won’t be driving it next year either based on current logic.
  • Lynnmor wrote:
    rhagfo wrote:
    Well why didn’t you do some day trip driving with it during the summer months?
    7,000 miles of day trips may be a bit too much.

    There is no drain plug for the DEF, that might cost 25 cents, instead you need to siphon it out if you want to replace the fluid.
    It is probably worse than that. My 2011 Silverado had a mechanisim to prevent siphoning. Basically a spring loaded door in the fill line. The Fords are likely the same. I believe it is a Govt. anti tampering requirement.

    I had to remove the tank to drain mine.

    DEFs shelf life varies a LOT with temperture.
  • rhagfo wrote:
    Well why didn’t you do some day trip driving with it during the summer months?
    7,000 miles of day trips may be a bit too much.

    There is no drain plug for the DEF, that might cost 25 cents, instead you need to siphon it out if you want to replace the fluid.
  • rhagfo's avatar
    rhagfo
    Explorer III
    Well why didn’t you do some day trip driving with it during the summer months?
  • It’s probably OK, but you can get on Amazon and buy an inexpensive refractometer that will tell you if it still has the correct 32.5% urea. Some refractometers can also check multiple fluids, like antifreeze, windshield washer fluid, DEF, and battery acid.

    Diesel Exhaust Fluid doesn’t degrade nearly as quickly as people assume. For example, at 86°F, DEF has a shelf life of a year. But, don’t equate shelf life to spoiling like food, as DEF will not “go bad”. It will lose some effectiveness, and the SCR will dose at a higher rate, but it won’t “go bad.” If maintained at a constant temperature, DEF manages to stay good for several months. For example, at 74°F Diesel Exhaust Fluid has the shelf life of 44 months.

    :):)
  • 4x4ord's avatar
    4x4ord
    Explorer III
    I've read that the shelf life of DEF is one year, but we buy it in bulk and have stored it for years. Deisel exhaust fluid is naturally clear so if it appears cloudy or colored, it’s likely contaminated or old.
    Years ago I bought some jugs of DEF from NAPA and poured it into one of my trucks. When I got to the bottom of the container there was an awful lot of crystals in the bottom of the jug ... so much so that the jug spout plugged off. I left it in the truck and ran the truck as normal without any problems. Apparently bad DEF can cause issues.
  • Shelf Life ...2 yrs in a SEALED Container

    Save bet ---- drain and refill with NEW