[DutchmenSport]

I can go about 4000 miles on a full tank of DEF before I have to add any. On occasions, it's been longer than a year to travel that 4000 miles. Other years, I'll drive that in 2 months. But even the long term duration between fills up has never been a problem for me. I keep a jug of DEF available all the time. Sometimes, I'll have it in storage for several months before using it. I keep the container in the front pass through storage area in my Montana, Summer or Winter. When traveling, if for some reason, I get the warning Def-low, I can add some right on the spot (or next fuel stop). I'll then buy 2 new jugs (usually Wall Mart), and finish topping off the tank, which usually does not take the full second jug. I'll then put the remaining bit of unused and the full new one in the trailer and keep it. After about a thousand miles, I'll add the remaining from that partial one. Then wait for the Low Def indicator to come on again and repeat. I've never had any issues. Again, it could be a year between fill ups or it could be a month, depending on how we are traveling. Def ages the same no matter what container it's stored in. The truck tank or the container it's sold in.