Towing - Overdrive or not

[tom.burns60]

I have a 2003 F250 SD Crew Cab 2x 4 7.3 turbo diesel and pull an 18'-6" boat. It's like not having anything behind me. From what I have read in my owner's manual, I am not supposed to tow in Overdrive, but when pulling a hill in the summer, the oil cooler kicks in robbing the engine of some power & pushing the temp gauge up. If I leave it in OD, the oil cooler does not kick in and temps drop down.

The GVW of the boat & trailer is nothiong. What is best for gas milage, protection of the tranny and component temperatures?

[greenbeast]

Tow with the OD on, unless you are going 50MPH all the time.

[dereku]

I leave my OD off until I hit about 55 or 60 it bogs the engine too much below that.

[Airstreamer67]

I tow a 6K travel trailer and leave it in overdrive unless and until the transmission starts "hunting," that is, constantly shifting back-and-forth from OD to third. At that point, I take it out of OD until the hills smooth out. My differential is a 3.55.

My 1996 F250's drivers' manual says to do what I'm doing. Yours sounds like it gives different advice.

I get my best MPG (around 14) towing the trailer as noted at 55 to 60 mph.

[WAFlowers]

I do what Airstreamer does but with a 13K 37-foot 5th wheel (see the pic in my sig). On our last long trip (4,000 mile round trip from Florida to our B&B in New Brunswick, Canada to Toronto and back, including some side trips) we averaged 10-12mpg doing 65-70mph.

I'll start up a hill then turn off OD when it drops out anyway, then turn it on again once the speed comes back up to cruise.

Certainly on flat or downhill terrain, OD works just fine and helps fuel economy.

[SuperCrutyPS]

I agree with leaving it on unless I'm going up hills. I pull a 12K 5th wheel. I was running flats with OD off and the tran ran hotter. I re-engaged OD and saw the trans temps drop back down to normal.

[ttyR2]

Curiously, I was cautioned NOT to use the OD gear on the stick tranny in my F-350 by a friend. It was interesting listening to him try to explain why, and he just couldn't grasp the difference between OD on a stick and auto tranny.