No way to tell until a total tear down but just a wild guess is the oil filter rubber stopper was damaged, thus the low oil warnings earlier. Possibly some damage to the bearings occurred at that point but didn't totally fail until the high speed, heat and rpms at Flagstaff. Engine failures are very rare (so far) in these.
If I am right, the dealer did the right thing with the oil cooler but that can't fix scored bearings. I hate this is your first post, can you share if it is under the diesel engine warranty still? A 2018 should be unless it has extensive mileage and yours did not. Hoping for the best for you.
(Edited for my usual misspellings and such)
If I am right, the dealer did the right thing with the oil cooler but that can't fix scored bearings. I hate this is your first post, can you share if it is under the diesel engine warranty still? A 2018 should be unless it has extensive mileage and yours did not. Hoping for the best for you.
(Edited for my usual misspellings and such)