A lot of this has to do with the propensity of people to believe everything they read and see on the internet and social media, and then regurgitate it as if it is gospel. There’s an almost endless cacophony of posts about how it’s “useless” and “troublesome” on social media. Meanwhile the vast majority of owners have little to know real understanding of how the system functions, the science behind how it works, and the reality which is that the fluid does indeed do what it is intended to. The simple truth is that the science is sound, the system does what its intended to, it is a far better way of reducing NOx as opposed to EGR cycling, and on the whole the systems are incredibly reliable. I would happily wager that a significant portion (perhaps a strong majority) of the DEF related failures in these trucks can be traced back to some aspect of owner / operator error. Mishandling or improper storage of the DEF itself, using poor or outdated fluid, carelessly filling the tank and allowing contamination inside, overfilling the tank beyond its rated capacity, running the tank carelessly low on fluid, etc etc.