Stale DEF

Shelf Life ...2 yrs in a SEALED Container

Save bet ---- drain and refill with NEW

Always treat a diesel the safe way.

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.

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.

:):)

Well why didn’t you do some day trip driving with it during the summer months?

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.

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.

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.

Direct quotes from the Peak Commercial and Industrial website regarding DEF shelf life and contamination:

• The best temperature for storing DEF is 77°F. Higher temperatures will not affect the quality of the DEF, but will impact its shelf life. The quality of DEF also is not affected if the fluid freezes. When stored under optimal conditions — between 12°F and 86°F — DEF has a shelf life of up to two years. If stored in warmer temperatures, shelf life decreases.

• If you suspect the DEF has become contaminated, do not use it. You can use a DEF refractometer to test the purity of DEF. A refractometer is designed to measure the concentration of water-soluble fluids. It works by measuring the refractive index, which is the speed at which light passes through a liquid. To check the purity of DEF, apply a few drops to a refractometer that is capable of measuring urea concentrations. They are available in single and dual-scale models. The single scale version shows the percentage of urea by weight, while the dual-scale unit also provides a refractive index scale reading. A single scale version is fine when checking for water dilution.

IMHO, you should be more concerned with the purity of DEF than the age of it. Aged DEF will be used at a higher rate than fresh DEF. Contaminated DEF will cost you repair time and money. That was why I bought a refractometer in the first place. If DEF is diluted with pure water, how are you going to know?

:):)