DEF Math
The owner's manual says my truck has a 5.5 gal DEF tank. I waited until I was down to 1/4 on the gauge, just above the red zone, and added a 2.5 gal box of Blue DEF from Advance Auto. Now the gauge ...
Forum Discussion
Old-Biscuit wrote:
DEF is an aqueous urea solution made with 32.5% urea and 67.5% deionized water.
Brand shouldn't matter
Brand shouldn't matter, but I have a different experience. I had always used Peak Blue DEF but a local farm store had some off-brand DEF that was $7 for a 2.5 gallon container. I used the cheap stuff to fill up prior to a long trip and about 100 miles in I got a CEL and noticed that my DEF gauge started dropping MUCH faster than usual. At an O'Reilly's I used their scanner which showed a code for "Insufficient Catalyst". I topped off my DEF tank, but the CEL came back on and the excessive use of DEF continued for the trip.
When I got home I siphoned out the entire DEF tank and refilled with Peak Blue along with clearing the code. That was 6 years ago and I've used Peak ever since and have never had that code again.
Was it cheap DEF that was made at a bad spec? Maybe. Was it just old DEF that had been stored improperly and degraded? That's probably the more likely scenario. However, I decided that my track record with name brand Peak and the problems with the one use of the cheap stuff was enough to convince me to use the name brand and not risk problems just to save a few $$.
I may be spending more for no good reason, but I don't like taking the risks.
KJ
