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Old 04-01-2023, 05:43 PM   #1
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Question DEF in truck when sitting long time

I usually park my truck for 4-6 months during the winter. Sometimes i drive it for a week or 2 and park it again. So is the DEF going to go bad? Been doing this for several years, but just wondered if some day I start the truck up and it gives that Bad Def warning?

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Old 04-01-2023, 07:41 PM   #2
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If you have been doing this for years with no issue it sound like you have answered your own question.

Probably depends if you got it from the gas pump, Walmart, a high dollar store or you made your own.
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Old 04-02-2023, 07:46 AM   #3
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As I noted on a different thread, DEF is good for one to three years depending on the temperature at which it is stored. High storage temps shorten it's life.
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Old 04-02-2023, 07:56 AM   #4
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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.
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Old 04-02-2023, 03:11 PM   #5
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I forgot that it can sit a year. I live in Mesa az, so it can be hot, but garage is about 80-90 degrees for Sept/Oct and again in April/May before we use the truck again. So I guess that isn't too much sitting. Thanks everyone.

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Old 04-02-2023, 07:43 PM   #6
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If you have a newer truck you'll go through a lot more. Mine uses about a gallon to 250- 300 miles.
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Old 04-10-2023, 06:01 PM   #7
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Just did 2000 of a 3000 mile trip and had to add 3 gallons to the 7 gallon tank.
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