Ok, tbh I don't know for sure, but let's go over this

you put that blue devil fluff in ur engine, that has a extremely high viscosity and is designed to swell all seals it comes into contact with. There are 40+ little seals gaskets, and o-rings in that engine. When some of them expand it can cause clearence issues, although minor ones, that could cause clicking till they get re-worked in

the higher viscosity can also cause problems, untill it gets fully mixed in and burned fluid.

Older engines, especially fords, usually develop lifter ticking, my dads 01 4.0 explored ticked pretty good at 40k miles. They are roller lifters as well so they have moving parts that can ware and tear.


There are so many possibilities it's not even funny, like snaw said, could of even of been a price of dirt