Originally Posted by firehawk198

I found it delays the shift by letting it go to a higher rpm such as taking off loaded it might shift at 2200 rpms in none tow mode but tow mode will hold it to about 2600 rpms. Found when I am going down hills mty I just pop it in tow mode to let it downshift to slow it down with out using the brakes so much too.

Originally Posted by firehawk198

Some of my friends that I have met at campgrounds in the past have said they got 18 mty and 12 towing. Talk can be cheap sometimes even by the nicest guys. For some reason it seems to be human nature to exagerate. Yes at some points they can get that type of milage. One easy trip mty to Maine and back 400 miles I got 16.8 on my computer Once part time towing I got 12mpg. It would be easy to brag and say I got that all the time. For the guys that write down their milage and keep logs it may look like My 450 for the 1st 2,000 miles averaged 11.7 hand calc. towing about 17k 8.726 for 2,000 miles. Now that I am broken in,last tank was 13.46 rural and some city. computer showed 14.3(sure was off). Do not expect quite this good but would be happy with 12.5 or so mty. Yes lighter trucks with 3.73 gears traveling slower nonstop can get higher milage. Also did you scale out. I use to think I was towing 13,500 when I scaled this year found out my gross was 16,650# over the dry weight of my truck 8,700# giving a total of 25,350. Found it only downshifted on steeper hills in the Poconos. You might have spent a little more time in drive than OD.

Originally Posted by T-Trash

Thanks your comprehensive remarks. You confirmed that a lower geared rear end would have been a better choice for towing but on the other hand not so great an improvement that I have to keep beating myself up about buying a 3.73. If I run empty I can get 18 to 20 mpg on the interstates but it worsens quickly with hills and high headwinds. Running empty around Minneapolis I get a pretty consistent 12.5 mpg (about the same as I got with my F350 V10). So, perhaps the 3.73 rear end was not such a bad choice because in a year or so we intend to go full-timing in our trailer and the truck will become our only vehicle. We probably won't tow the trailer more often than every month or two in that life style. Nevertheless, I want to save as much fuel cost as possible - I bought a bottle of Ford's Cetain Improver so I'll see if that helps.
Regards,

Originally Posted by SaharaF350

why are you towing at 80? depending on the gears you have that's high rpms, i have the 4.30's and above 65 fuel economy is gone... you shouldn't be haulin *** like that with a load anyways. I pull a 48 foot enclosed trailer, loaded with heavy cars and i get mid 10's at the moment. and i don't take it easy on this sob so that's pretty good fuel economy for the work it does to me.

Originally Posted by Snowman_175

I have a lead foot but i guess i need to change my driving habits. I guess this ain't my F150...

then again my buddy has an 08 350 with the dual wheels and he was pulling the same amount of bikes and he got 8.2 doing the speed limit and he's an older man who drives real well. So there may be a speed issue but the diff is not that dramatic.

Originally Posted by avmike

My 08 has a tow/haul selector on the end of the transmission shifter. I leave it in that mode when I am towing and still run through all the gears. If I deselect it and go into OD, I find I must use more accelerator to maintain my speed, plus I don't have the down hill braking that the engine seems to give me in the tow/haul mode. My RPMs or turbo readings do not change from one to the other, but going up even a slight grade, the transmission will start looking for gears in OD. So, I think driving in OD while towing is probably a wash.

I do not understand exactly how the transmission works, but even though you run through all of the gears, it feels more responsive and powerful in the Haul/Tow mode as opposed to OD.

Originally Posted by SaharaF350

My mileage improved with miles. at about 5k it went up to 9's, at about 7500 it went to 10's, by Monday I should be at 14,000 we'll see how it does there. I've had the truck a total of 3 weeks now

Originally Posted by turban8r

14000 miles in three weeks? At an average of 50 mph that is 280 hours. 21 days = 504 hours. That is a heck of alot of time behind the wheel.