Mines only got about 13,500 miles.
So far, have only added def once.
It was sometime after the 1000 mile warning, which iirc, occured with about 22% on def gauge (the math on those don't work, but I think that's what it was.)
Currently it's at about 250 miles to empty. Since it's below the '300 mile to empty' warning, so gives a reminder each time it is started. I
When it gets to empty, the next warning is 500 miles to 65 mph speed limit'. Still debating if I will want to see that message.
(after 65 mph limit, it's another 75 miles to 55mph limit, then another 75 miles to 5 mph limit)
I'm not using the truck much over the winter. My decision may depend on when longer runs or higher usage enter the picture.
DEF consumption is related to the amount of fuel used. For comparison, lifetime this one is somewhere around 18 mpg.
Pavillion450, how much def are you adding each time?
2018 GMC 2500 L5P CCSB 4x4 Denali - Mineral Metallic; previous '11 LML, '10 LMM and 04.5 LLY