I have a 2004 V-10 2wd that will be used to tow an 8,000 lb trailer. Is it OK for me to tow, mostly on the flat, (OH to FL) in overdrive so long as I keep an eye on the transmission temperature gauge ? The trucks owners manual says that shutting the OD off will not affect fuel economy but that doesn't seem logical to me. Oh, by the way, I will be installing a 5 Star Tuning 87 octane towing tune. Your thoughts?

 

the only time you need to turn OD off is if it is hunting between gears.

with my setup this happens in rolling terrain and long grades at certain speeds. i can usually stop the hunting by changing the throttle position as well.

 

You don't mention your tire size or gear ratio, both of which will influence how well it performs towing in OD.
On my V-10 with an effective 4.39 ratio and 5Star's 89 Octane Performance tune (I like how it operates better than the actual Tow tunes) it typically can stay in OD without hunting on all but the biggest Interstate Highway grades here in the East towing between 60/70 MPH pulling the big 12K TT. A Numerically lower gear ratio, like the common 3.73, will drop down out of OD more quickly on a climb but that what it's designed to do, what you don't want is for it to be shifting in/out of OD frequently on the flats or gently rolling terrain as that will build too much heat. Keeping it in OD more will deliver better MPGs, at least that has been my experience.
Do you have a means to monitor the trans temperature besides the dash gauge (idiot light), I think keeping an eye on the temp is a good idea for any serious towing with this trans.

 

I'm running a 100% stock 2004. 16" wheels and tires with 3.73 gears. Fortunately my truck has a trans temp gauge and not just an idiot light. Thanks for the reply. I'm curious, why do your run 89 octane rather than 87?

 

Also, I would not rely on the factory temperature gauge. They are just dummy gauges at best.

 

That factory dash gauge is really just and idiot light with 3 or 4 set positions, not a real actual full sweep gauge, get something that will allow for you to see the actual real trans temp while towing. There are various Apps that paired with the right ODBII dongle will show the trans temp (and a lot of other data) or a stand alone trans temp gauge with the sensor installed in the test port on the side of the trans, that what I use.
As to why I use the 89 Octane tune rather than the 87 tune, it works better for how I use my EX. After a good deal of testing on our trips I found that the 87 and 89 Octane Tow tunes were too aggressive to downshift out of OD on a climb when the engine was still making sufficient power and torque to handle OD. A better choice for those who need to be the first on to the top of every hill, but that's not me. With the Performance tunes you can hold OD longer on a climb with higher throttle openings.
While towing on a given "standard" grade at 60 MPH with the stock tune it will hold OD up to about 45% throttle opening before forcing a downshift. With the 87 Octane Performance tune loaded at the same speed on the same or very similar hill it will hold OD up to about 54% throttle opening and with the 89 Octane Perf tune loaded (and matching 89 Octane gas) it will hold OD up to about 64% throttle opening. On longer or steeper grades I will allow a few MPH to bleed off if I feel that that will allow me to crest the hill in OD at 55+ MPH, if that doesn't seem possible I will roll a little more throttle in and let it drop out of OD where it will easily maintain whatever road speed I wish on the climb. Due to the engine working at slightly higher RPMs (where these 6.8 make better power/tq) this all works even better at higher speeds, like 68/72 MPH, this better approach speed allows more grades to be topped in OD and you have even more elbow room to bleed speed down to 55-ish if you choose to. The more time you can spend in OD the better your MPGs will be and I always have fuel economy on my mind as I'm a Hyper-Miler in real life with my 63 MPG '94 Geo Metro. On our mostly highway trips towing the big TT (12,000lbs, 41' long and 12' high) I typically get between 8 & 9 MPG with 2 trips over 400 miles of 9.5 MPG as my best to date. A 10 MPG towing trip is my Holy grail.

 

me thinks it only has 3 settings
1. off
2. middle
3. already melted

 

Well, no.

It isn't a real gauge, but it isn't THAT bad. The gauge stays cold until the trans gets up to 50°F. At 50°F it jumps to the middle. It stays in the middle until 230°F, where it moves to the yellow. At around 260°F it moves to the red. None of those temperatures are hot enough to melt the transmission.

 

260° isn't to hot? I was always told 200 is ok, 210 pay attention, 220 back it down, and 230 pull over and cool it off! I can't imagine getting to 260 in the trans. Infact, I've never been above 200 towing TT.

 

my sarcasm aside thank you for the real explanation.

the only time mine ever moved off Middle was up Baker grade out of Barstow Ca in the Mojave desert( yes the one largely responsible for modern radiator engineering) while towing 11k lbs in 110* summer heat, crazy part that was at night .

it went from middle to pegged red and sitting on the side of the road in mere minutes

 

But we enjoy sarcasm now and then. Melting may occur....

 

me too, but the real answers from the trans man are even better

fwiw, have a real mechanical gauge and watch it like a hawk now, or at least when towing hills and hotness.

 

At 260°F you should be taking action to cool it off. Idling or fast idling in park or neutral are good ways to cool it off.

What you've been told is several decades out of date.

 

I've run test vehicles up Baker Grade. Much more often we would run up the Davis Dam grade, AZ 68 heading east out of Bullhead City AZ. It was close to our proving grounds in Yucca, AZ. Since I left Ford this proving ground has been sold to Chrysler.

That was a rise of about 31°F, going from 229°F where it would be in the middle, to 260°F where it would be in the red.

 

doing some SAE J2807 testing where ya