Hmmm....wonder if they figured out what was going and fixed it in the 2019 models. Anybody got a 2019 with this issue?
Some good questions.
As for figuring out why the problem, I imagine a scenario where somebody handed out a bunch of undersized rings at the engine factory and about lunchtime the foreman realized it, slapped the worker's hand, then distributed the right-sized rings and hoped no one would ever notice. After all, whats a couple thousandths of an inch? [Just noticed "thousandths" -- can you think of any other words with 5 consonants in a row?
I doubt FCA will ever admit to a blunder or issue a recall. Like the unnamed foreman in my posit above, they probably figure it didn't happen to that many and if they have to replace a couple engines when customers complain they'll do it rather than issue a recall to replace however many got made before the mistake was found. After all, its not a safety issue so I doubt NTSB is interested.