I have a 99 F-150 with a 5.4 in it. it currently has 44,000 miles on it. I d omake sure that all maintenance is done. Realistically, how many miles can I really put on this without worrying about a major repair?

 

All depends, how much do you use it for driving, towing, how much modding you gonna do? The wonderful thing about these modular engines is that the may suck when it comes to economy but they seem to last forever. 5.4 in its current design has been tested to run safely on boost for a long time. If it can go 100,000 miles with 8 lbs of boost it'll go 500,000 without it.
Where do you live?

 

I live in KC, MO. I do tow a boat once in awhile. But what exactly is boost? I do not understand that reference. :_)

 

jordan12- He's referring to supercharger boost.