This may be a no brainer but I have to ask. I have a 2000 Ford F-350 diesel with 4.3 gears. I am pulling a 10,000 pd. 5th wheel.

Do i have to turn the overdrive OFF everytime I tow?

 

I wouldn't. Ford has recommended that unless it's lugging down that you leave it in OD. If it keeps switching in and out of OD, I would also turn it off. So if you are up and down hills, leave it OUT of OD. If I remember correctly, MS does NOT have hogn hills, so I'd leave it in OD. I have also used Cruise in that situation too.

 

just pay attention to the shifts...

if it is switching from OD to D often, go ahead and lock it out.

 

Tow with the tallest gear that the torque converter will lock and stay locked. I have been towing a 10k lbs travel trailer with my E350 V10 in overdrive for 4-5 years and more than 10k miles. I shift down when necessary to keep the speed up and torque converter locked.

 

I have been towing for 5 years with my truck in overdrive. I was hearing the transmission shriek going into OD on this years trip to Florida. Got my tail chewed by service writer in Florida for pulling in overdrive. My home diesel tech told my that if the tranny was shifting back and forth a lot to switch it off until I got on a smaller or no incline. I still do not know who is right. I hope it will be less of a problem with my new truck....

 

That's why I drive a manual shift. YOU control the shifts. My wife and her van drives me nutz. When I first start off, I turn OD Off. (We live in the city) She leaves it on always, and it shows... When I get to unobstructed hi-way, OD goes on. We come to an interchange below 40, OD is off, etc. My truck, OD isn't there till I get there. Then, it's hittin' the coffee and settlin' for the ride.
Towing a trailer is the same. Listen to the motor and watch the tach.