Help me to understand DEF usage. Please

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Aug 28, 2017 | 10:29 PM

#16

Painted Horse

Lead Driver

Joined: Nov 2005

Posts: 5,227

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From: Kaysville Utah

I almost never look at my DEF level. When I'm at a station that sells DEF at the Pump. I top off. I've only seen the 500 miles to empty message Once on this 2015 truck in 80,000 miles and only a couple of times on my 2011 truck with 150,000 miles. I just don't think it makes much difference whether I top of with 1 gallon or 4 gallons. I stopped buying the jugs and just pump at the stations and top off what ever it needs.

Aug 31, 2017 | 08:52 PM

#17

lanedecamp

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Joined: Oct 2012

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Quote:

Originally Posted by polarlys

I began this thread with my original question. I'm just about at 4000 miles since my last DEF fill and MORE than 1000 miles since I had the 500 mi warning appear. Perhaps it was a fluke when it showed up but I'm still looking for the 200 mi warning. The only reason I wait is to make sure that the warning are reliable so we'll see how it pans out.
These past few months have been a mix of driving with / without our travel trailer and I'm just curious to see how the DEF consumption is.

ThanX all for the discussion and advise.

Everyone's been talking around the answer, but it's pretty simple: You can't rely on the accuracy of the truck's DEF gauges, either 500 or 200 mile. Nor is there a consistent rate of usage. If it runs dry, it'll sense that at another point than the in-tank gauges and will put you in limp mode or turn your engine off entirely. So you're better off filling the tank every 3000 miles or so and not worrying about it after that. I do an oil change every 5K miles and top off DEF at every 2.5K interval. It's easy to remember. There's no reason to let levels get unnecessarily low. You can always get a handle on usage by measuring how much you put in every 2.5K miles. That's about as useful as how many miles before the 200 mi light goes on.

Sep 6, 2017 | 04:31 PM

#18

polarlys

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Well. Since I began this thread I might as well end it too or at least keep up with it. Just yesterday I got another 500 mile warning. This one popped up right about the mileage I thought it should be. Something set the first one off prematurely which caused me to generate this inquiry. I suspect all's well with my warning system and I'll monitor it and fill it when I get the 200 mile indicator. So, by the time I get the 200 mile I project that I will be in the neighborhood of 4000 miles since my last re-fill.

ThanX all for your discussion and input. At least I think I understand my DEF consumption a little better now.