I have a '04 F250 FXA Lariat LB. It has 12,756 on miles and I have had two oil changes.

Question: I was getting 15.5 to 15.6 miles to the gallon prior to my first oil change. After first oil change mileage went to 15.4 to 15.5 miles to the gallon til my second oil change. After my second oil change the mileage went to 15.3 to 15.4. Then I pulled my fifth wheel for 500 miles and after the trip was over I was getting 15.1 miles to the gallon. I am still getting 15.1 miles to the gallon empty after two fill-ups. Am I just crazy or is there possibly something going wrong?

Also, would a fuel conditioner possibly help? IF so what type and brand??

 

Barometric pressure, wind and a whole lot of other factors could account for tenth of a mpg. I wouldn't worry about it unless I saw bigger mpg differences.

 

Silly me...
but have to ask the usual questions...
are you resetting your overhead ?
Have you reset the overhead anytime ?
how are you calculating your mpg ?

are you filling it up until it overflows to the same level each time ?

SO many variables... .4 mpg is almost too close a tolerance to measure....

 

I am using actual miles driven divided by the amount of gallons put in the tank. ie.. miles at last fill-up subtracted from current miles at next fill-up divided by gallons put in tank at current fill-up.

What did you mean by "resetting the overhead"???

I am filling up til the first shut-off everytime.

 

Your answer indicates you are doing the correct manual calculation method...

I was just asking if you were using the overhead, lie-o-meter, for your mpg calculations,
it needs to be reset periodically or else it's just too big a sample to get accurate current mpg...

 

Now you have my curiosity. How do you reset the lie-o-meter??? Did not know it could be reset.

 

Push both buttons at the same time. Tim

 

What's the weather been like throughout the history of the truck? I'd expect some change from winter to summer just because there's less O2 in the air on the hotter days.

It could easily go the other way too in the winter I'd think, because you might tend to let the truck idle more before driving.

Tire wear and tire pressure could be a factor as could traffic. Pretty tough to nail thinks down to a tenth of a MPG I'd think. . .

 

Bought truck in May '04. Weather has always been summer time. HOT as @#@#!!!

 

@#@#!!! means Hades right

 

CORRECT. That is a more politically correct of stating it.

 

Labman: Where in NE Texas are you?

 

Speaking of Hades, my mom is out here visiting because of the new baby. It has been so hot here in San Diego that she's calling to see if she can change her flight to go home to Nebraska early.

They have AC at home and we don't here at our house. It's 86 deg and 65% humidity right now. Rather balmy I think, but too hot for her . . .

 

They call that a cold front here in Texas.

 

Ohhhh, what I wouldn't give for that kind of weather.....it's been 45 here all week