Overdrive on or off?

[Fla904]

I have a class C gas ford v-10 motor home. I noticed today it drives much smoother, accelerates faster, and switches gears smoother with overdrive off. The whole time I've owned it overdrive was on. Which is better to use highway driving and which is better on the engine in terms of engine wear?

[RBPerry]

Generally automatic transmissions are programmed to shift based on load and RPM, the engineers that develop these shift points know what there doing, what they don't know it the environment your engine is running in. One thing I do know for a fact is if a transmission is shifting constantly it is building heat, and wear and that is not a good thing. For me I want my transmission to keep my engine close to it's peak torque curve, that is going to put the least amount of strain on the engine and produce close to the best fuel mileage.
A standard transmission normally doesn't care how many times it is shifted as long as the driver isn't banging gears. Some drivers do have a tendency to lug an engine that is backed by a standard trans.

[Grit_dog]

frankdamp wrote:
If you had a car with a 5-speed stick shift, would you never use 5th speed? What you're doing is the same, IMO.

Absolutely, if you couldn't pull 5th gear or kept downshifting around every corner.
However, that's the main advantage of a manual trans, being able to pull high gear longer without damaging the transmission.
With a stick you can pull any gear you want until the engine won't pull it (not talking about lugging a diesel and egts here) and you'll do no transmission damage. With an auto trans pretty much regardless of design, if you're not able to keep the converter locked and/or downshifting a bunch you're making unnecessary trans killing heat.

[frankdamp]

If you had a car with a 5-speed stick shift, would you never use 5th speed? What you're doing is the same, IMO.

[RBPerry]

I'm a retired truck mechanic, most over the road trucks have a transmission temp gauge. Reason being heat is one of the things that kills automatic transmissions. If the transmission is shifting frequently then it is being overworked and will heat up. The heat breaks down the fluid and that in turn causes excessive wear. Changing the AFT fluid every 30k miles will prolong the transmission life considerably. My personal belief is if you can run in OD and hold that gear you should be fine, I do know there are two schools of thought on this issue and I have technicians argue it back and forth.

[time2roll]

Off is fine too if it just drives better.

[Grit_dog]

Simple. Leave OD on if the trans is holding that gear. Turn it off if keeps downshifting or even unlocking the torque converter.
In hilly terrain, just lock it out. Triton engines like to rev and your transmission and brakes will thank you for it.

[dodge_guy]

Also you can have the PCM reprogrammed to provide optimal towing/loaded shift strategy. I did just that with my V-10 Excursion and it dramatically changed how the truck performed with my 9200lb TT.

Check out 5star tuning, they have a very good reputation with the triton motors and towing. With them it's not all about power but the overall performance for what you want it to do!

[Deleted_per_op]

wa8yxm wrote:

Dick_B wrote:
I would be in overdrive unless it starts to downshift frequently. What is frequently? Make it 15 minutes or less.

The manuals say things like "not in hilly country", "not if towing" and "Not in bad weather" as a general rule.

But the advice is the best advice.. If it is constantly "Hunting" for the right gear (Shifting frequently) turn it off. but if it's shifting into Overdrive and staying there for miles and miles and miles and miles (how far CSI-Cyber adn the WHO can see) Well... (yes that is a joke), Well then engage it. and leave it engaged, Makes a major difference in MPG on my Class A.

Here's a ham radio guy showing his age! He remembers the band "The Who" singing "I can see for miles and miles.....". I think I read about that in history class. (or maybe not) :B

[wa8yxm]

Dick_B wrote:
I would be in overdrive unless it starts to downshift frequently. What is frequently? Make it 15 minutes or less.

The manuals say things like "not in hilly country", "not if towing" and "Not in bad weather" as a general rule.

But the advice is the best advice.. If it is constantly "Hunting" for the right gear (Shifting frequently) turn it off. but if it's shifting into Overdrive and staying there for miles and miles and miles and miles (how far CSI-Cyber adn the WHO can see) Well... (yes that is a joke), Well then engage it. and leave it engaged, Makes a major difference in MPG on my Class A.

[dodge_guy]

I checked the OP`s sig, thy have a 98 E350 chassis. so with that I would leave O/D on and only lock it out if it shifts in and out of O/D frequently.

[bukhrn]

My answer was going to be, "depends", but it looks like it's been answered pretty well.

[DrewE]

Is your button labeled "O/D Off" or "Tow/Haul"?

If you have an "O/D Off" button, it's an older chassis with the four speed transmission and the button simply locks out the fourth (overdrive) gear. This can be useful when driving through areas of rolling hills, etc. You can also make it kick out of overdrive by pushing the accelerator down far enough to make it downshift.

If it's labeled "Tow/Haul," you have a newer five or six speed transmission, and the button does not disable overdrive. It instead alters the shift logic some to optimize it for heavier loads--tending to stay in lower gears longer, downshift for engine braking, and avoiding unlocking the torque converter so as to keep the transmission temperatures cooler, perhaps among other things. Since a class C motorhome is a large load for the chassis, it's perfectly reasonable to leave tow/haul engaged all the time. It's especially helpful in hilly or mountainous areas.

[old_guy]

a mechanic told me if it has over drive factory installed it is OK to use it when on the open road. that's why it is there. like the above post states, if the tranny is searching for gears, it is time to turn it off and down shift. when the road is level or going down a hill, turn it back on.

[Dick_B]

I would be in overdrive unless it starts to downshift frequently. What is frequently? Make it 15 minutes or less.