Moved from a 01 F-250 7.3 to a 15 duramax dually. First tow with the same trailer the 01 pulled. The 01 was not a dually. Amazing, simply amazing the difference. MPG were 1 mile to the gallon less than the 01, which had a 3:42 rear end. The 15 has a 3:73. Was amazed that their is only .3 mpg difference between cruise and non cruise. The one question I have is how often do you have to put in DEF fluid. Had to refill at a little over 800 miles.This rig kept up traffic and was quick. Wonderful experience. Happy to have it. By the way the trailer is a 2013 5 slid Montana. Rig is very balanced and the tow haul mode really works.

Congrats on the new truck!Sounds like a well matched rig, hope you enjoy many miles!Can't help on the DEF question, I'm sure others will have an idea.Jerry

Did you fill the DEF tank all the way? Doesn't sound like it was full. I get DEF at Walmart in 2.5 gallon boxes for about $11.50. DEF tank is 5.5 gallons and usually lasts about 5,000 miles. Except under heavy towing mine might only last 3,000 miles.

Nope, did not fill before left. Not sure how much was in it. But it is suppose to be a 5 gallon tank (I think) and I put about 4 gallons in it. Got the fluid at Walmart, china's American flee market.

azdryheat wrote:Did you fill the DEF tank all the way? Doesn't sound like it was full. I get DEF at Walmart in 2.5 gallon boxes for about $11.50. DEF tank is 5.5 gallons and usually lasts about 5,000 miles. Except under heavy towing mine might only last 3,000 miles.Boy did you bend over at Wall mart? Generally at the truck stops DEF is $2.78 you paid $4.50!Generally my Dmax asks for DEF about every 3500 miles that doesn't mean it is empty but you need to fill in the next 1000 miles.I find filling from a nozzle rather than a container easier and more controllable. With an unscrupulous vender like Wallmart there is no guarantee that the DEF is even fresh. Bear in mind that DEF has a shelf life and getting it at a truck stop means fresh DEF.Go where the big boys play not at a "stick it to um" store.

It sounds like the F-250 was not really up to the task with that fifth wheel! Glad that you are enjoying the dually now! They are great, and compared to the older SRW, it will have stiffer springs, and handle the hitch loads much better. Good luck with the new truck! Enjoy! Someone else will also be enjoying the 7.3L too!Fred.

New Truck, first tow | Good Sam Community

Turtle_n_Peeps
Explorer
Oct 29, 2014
Average DEF is 1 gallon/ 1000 miles.
Campforever
Explorer
Oct 29, 2014
So far have been using tow haul mode, rpm's at 1550 and once jumped up to 1800 rpm's.
Passin_Thru
Explorer
Oct 29, 2014
You can use top gear towing if you have a tailwind, long downhill or flat where it doesn't take much power. I have a07 Duramax and it hasn't hurt it in 112,000 miles. Shift manually, keep RPMs up above 2300 while pulling and the fuel mileage will come up after it gets broken in.
MinnCamper
Explorer
Oct 29, 2014
Congratulations on the DMAX. You will love it- happy travels.
Campforever
Explorer
Oct 29, 2014
Played with the HDC a little on the way down, can for see relearning how to descend a mountain. Going on another short trip in November, then FL in early January. In regards to "bending over at Walmart" it was $11.49 per 2 1/2 gallons. Local truck stop was $3.99 per gallon. DON'T WANT AN argument but will do the best I can depending on the area pricing. This trip was south of Myrtle Beach, SC. Thanks for the tip about the truck stop though it may be difficult to fill. DEF tank access is under the hood on the right side. Could be a stretch for the hose.
tomman58
Explorer
Oct 29, 2014
Campforever wrote:
Moved from a 01 F-250 7.3 to a 15 duramax dually. First tow with the same trailer the 01 pulled. The 01 was not a dually. Amazing, simply amazing the difference. MPG were 1 mile to the gallon less than the 01, which had a 3:42 rear end. The 15 has a 3:73. Was amazed that their is only .3 mpg difference between cruise and non cruise. The one question I have is how often do you have to put in DEF fluid. Had to refill at a little over 800 miles.
This rig kept up traffic and was quick. Wonderful experience. Happy to have it.
By the way the trailer is a 2013 5 slid Montana. Rig is very balanced and the tow haul mode really works.

Going from an 01 to a 2015 is like moving from a cave to a Condo!
Great truck you should check out all the other towing features from the exhaust brake to the hill control. Great truck my BIL and I both bought 2015's and a 40' Jayco Travel Trailer to tow across the USA and more!
Oh Yeah baby! We don't like 5ers and I have towed a 35' TT for 90,000 miles and didn't even know it was there with a 2008 Dmax. Still wolrds of difference with the new one.
Golden_HVAC
Explorer
Oct 29, 2014
It sounds like the F-250 was not really up to the task with that fifth wheel! Glad that you are enjoying the dually now! They are great, and compared to the older SRW, it will have stiffer springs, and handle the hitch loads much better.

Good luck with the new truck! Enjoy! Someone else will also be enjoying the 7.3L too!

Fred.
tomman58
Explorer
Oct 29, 2014
azdryheat wrote:
Did you fill the DEF tank all the way? Doesn't sound like it was full. I get DEF at Walmart in 2.5 gallon boxes for about $11.50. DEF tank is 5.5 gallons and usually lasts about 5,000 miles. Except under heavy towing mine might only last 3,000 miles.

Boy did you bend over at Wall mart? Generally at the truck stops DEF is $2.78 you paid $4.50!
Generally my Dmax asks for DEF about every 3500 miles that doesn't mean it is empty but you need to fill in the next 1000 miles.
I find filling from a nozzle rather than a container easier and more controllable. With an unscrupulous vender like Wallmart there is no guarantee that the DEF is even fresh. Bear in mind that DEF has a shelf life and getting it at a truck stop means fresh DEF.
Go where the big boys play not at a "stick it to um" store.
Campforever
Explorer
Oct 29, 2014
Nope, did not fill before left. Not sure how much was in it. But it is suppose to be a 5 gallon tank (I think) and I put about 4 gallons in it. Got the fluid at Walmart, china's American flee market.
azdryheat
Explorer
Oct 29, 2014
Did you fill the DEF tank all the way? Doesn't sound like it was full. I get DEF at Walmart in 2.5 gallon boxes for about $11.50. DEF tank is 5.5 gallons and usually lasts about 5,000 miles. Except under heavy towing mine might only last 3,000 miles.

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