F250 - 2008 breakin period and expect MPG

Just bought a new F250 CrewCab 5.4L 4x4 Super Duty. I have read the manual
and it says not to Tow for the first 800 miles or so.
I have babied my baby as I want this truck to last me ~ 15years.. I now
have ~ 800miles and I noticed my fuel economy sensor report an initial
8.4mpg and as peaked to 12.2mpg and then drifted back to 11.8mpg.
My question is at what point (miles) is an engin considered broken in!
realisticly, does this break-in mean that I have reached my best fuel
economy?
What is the norm for this vehicle in the way of bext fuel mpg....
don't mis-read..I am not bitching about my fuel economy, I know I bought a
gas hog...this is a new vehicle and would like to gauge at what point my
engin has seatled in so that I can commence towing without affecting it's
efficiency for the long term.

P.S. Any special driving habit during the breakin period that will improve
the motors long term performance.

Pogo

On Jul 2, 3:02 am, "Pogo" <No_spam_marc@nospam> wrote:
> Just bought a new F250 CrewCab 5.4L 4x4 Super Duty. I have read the manual
> and it says not to Tow for the first 800 miles or so.
> I have babied my baby as I want this truck to last me ~ 15years..  I now
> have ~ 800miles and I noticed my fuel economy sensor report an initial
> 8.4mpg and as peaked to 12.2mpg and then drifted back to 11.8mpg.
> My question is at what point (miles) is an engin considered broken in!
> realisticly, does this break-in mean that I have reached my best fuel
> economy?
> What is the norm for this vehicle in the way of bext fuel mpg....
> don't mis-read..I am not bitching about my fuel economy, I know I bought a
> gas hog...this is a new vehicle and would like to gauge at what point my
> engin has seatled in so that I can commence towing without affecting it's
> efficiency for the long term.
>
> P.S. Any special driving habit during the breakin period that will improve
> the motors long term performance.
>
> Pogo

I don't think there is a magic number or switch or obvious indication,
it's just a precautionary common sense thing.
Other than hard stress, don't baby it too much. Drive it exactly as
you would in a non-towing environment.

I am keeping an excel spreadsheet for my 08' F150 5.4l flex fuel to
see what each grade of fuel costs me to run.

Date gal total price price / gal grade Miles at fill tank end mi Mi
this tank MPG $ per mile

05/31/08 26.800 $100.13 $3.736 87 gas 402.7 825.6 422.9 16.07 0.2368
06/07/08 26.324 $100.01 $3.799 87 gas 825.6 1209.7 384.1 14.48 0.2604
06/13/08 26.530 $104.50 $3.939 87 gas 1209.7 1646.6 436.9 15.79 0.2392
06/24/08 27.675 $83.00 $2.999 E85 1646.6 1949.5 302.9 11.41 0.2740
06/28/08 26.541 $86.50 $3.259 E85 1949.5 2269.2 319.7 11.50 0.2706
07/07/08 27.788 $85.00 $3.059 E85 2269.2 2594.1 324.9 11.17 0.2616
07/12/08 29.099 $96.00 $3.299 E85 2594.1 2903.1 309 11.28 0.3107
07/18/08 27.400 $105.75 $3.859 E10 2903.1 3304.5 401.4 14.52 0.2635


I uploaded a copy of the sheet into the yahoo groups f150ownersclub
group