I would agree with the rest, running a 2016 eco and no issue with the Def as I always fill it when it hit 1/2. Also not a big fan of the big rig pumps that dispense DEF, prefer to pick up the 2 1/2 gallon boxes. Sometimes I think the big pumps dispense it way too fast and may cause issues with the sensor. I bought the cap for the 2016, I like the aluminum as the plastic is cheap. I only bought it for the fuel side as the Def one seemed a bit more robust and I am not opening that one as much. I am going to try the 2016 cap on the 2020 I just bought but I had heard the pipe is a fraction smaller in diameter and it will likely require greasing of the O-ring. Will see if they ever get the truck here - covid plant closures are hampering my delivery.