I know all the previous years were 5.5 gallons. I doubt they changed that.
Be aware the gauge is not linear. It will take a long time before it actually moves. Unless I am going on a long trip I run mine down until the gauge says add DEF(or close to it) and only add 1, 2.5 gallon jug just so I don't have fluid sitting in there a long time and getting old. Especially in the hot south
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