I was reading in the owners manual about fuel recomendations.
Ford does not reccomend premium fuel at all in the the 5.4.
Whats up with that ?
Going to be towing a heavey trailer on vacation...wouldn't I want
to fill up with 91-92 octan for better performance ?

Thx, Tmeyers-Colorado
2001 XLT SuperCrew 4X4
ORP, 3.55 LS, 5.4
SnugTop flat top
Gibson Catback

 

Don't know for sure, but my guess would be that Ford believes that the truck will perform just fine on 87 reg. My observation is, after towing almost 5000lbs of boat and camping gear on a couple of long trips, that you don't need to switch to premimum. I never had any problems, but then again I was towing on flat terrain at sea level.

 

The higher octane buns slower and cooler. This will cause excessive carbon buildup in the combustion chambers. The engine has been engineered to run 87 octane. If you experience some pinging when you tow then I would try a higher octane fuel but otherwise just run 87. If you are running a "chip" with more agressive timing curves then you will need to run premium fuel, otherwise the 87 will be fine.
The older 4.0 liter Explorers were real bad about carbon build up because of people running too high of an octane fuel in them. the result was a carbon knock the sounded like a lifter tick. A lot of engines were changed for no reason because of this.