DEF shelf life
I have read that DEF has a definite shelf life, and I've heard figures of around 6 months. Given that most of us don't use our motorhomes in the winter, or at least like in my case, only on relatively...
Forum Discussion
bluwtr49 wrote:
If stored at moderate temps...it should be good for well over a year. After all it's nothing but water and urea (fertilizer)
DEF
Yes, it is just water and urea, and indeed it should last a year at moderate temperatures and out of the sunlight.
At the same time, it does degrade over time. But it is pretty darn cheap stuff, even at the highly inflated prices we might have to pay at some retail establishments.
I note that BMW dealers are supposed to flush and refill diesel car DEF tanks with every oil change to insure that no BMW owner is brought to grief by $10 worth of the stuff. (The DEF tank in my X5 35d holds about 6 gallons. So assuming the tank is relatively full, which it shouldn't be by the time oil change interval rolls around, $10 or so isn't an issue for anybody.)
I don't think the OP has a lot to worry about, unless, of course, he doesn't use up that tank full of DEF over the following summer. In which case, it might not be a bad idea to do a dump and refill each spring just to make sure.
