My daily driver 1991 LX has 240,800 miles on it, completely original motor and original T5.
I just took it on an 8000 mile road trip from Jacksonville, FL to the Rocky Mts, Great Salt Lake Desert, Four State Corners, Los Angeles, Roswell NM, and finally back to Jacksonville.
Got 30mpg like clockwork until I hit the higher elevation where it obviously dropped, but I had to hold that thing at 4000 rpms in 3rd gear floored to make it up some of the hills (the car was loaded with my junk). Did fine.
In Wyoming, the headwind was so strong that I had to use 4th gear at 70mph to maintain highway speeds for several hours, motor did fine.
This entire trip, the car did not consume a single drop of oil.
Cooling fan died in LA traffic, the motor produced so little heat that I didn't realize the fan was dead until I was home in Orlando, FL. Was stop and go traffic about 5 times, it just got "warm". My 5.0L would've died within a few minutes.
My point in writing all of this, is to show how much faith I have in this motor. I knew what I was going to put it through, and didn't even think twice. City mileage sucks, 22-25, which makes little sense considering how slow the car is, but hey, its a Mustang.
Did I mention it didn't eat a drop of oil?