Highway towing - Higher or lower RPM for engine life?

When towing long distances on the highway, is it better for engine life to use a higher gear or lower gear?

I'm getting ready to tow a trailer almost 2000 miles on the highway with my 1999 v6 5-speed. It only weighs about a ton, but it's tall and like a parachute so there's a lot of drag at highway speeds (~70mph). Is it better for engine life to tow in 4th gear at about 3100rpm and almost half throttle, or in 5th gear which puts it I think around 2700rpm and closer to 3/4 throttle? I've always leaned towards using the lower gear, but curious to hear everyone's thoughts on this.

 

With a manual I liked towing in 4th most of the time. Sure it was a little less efficient on gas but if needed you had power to start pulling a hill or pass some one with out the truck falling on its face. With autos I never tow in overdrive as the trans seems to hunt for gears more often.

 

Take it out of 5th frequently so the 5th gear doesn't get too hot and explode. Maybe switching the tranny oil over to synthetic would make a difference. Do the rear diff while you're at it. Edit: and grease the driveshaft u-joints

 

Run the highest gear you can easily maintain your desired safe speed at. If it becomes a struggle, drop down a gear or slow down.

No different than driving w/o towing as far as that particular technique.

Running drive line synthetics of the proper specs and making sure your cooling system and brakes are up to snuff is a given, because towing will certainly weed out weaknesses. So don't have any.

 

I would choose 4th gear instead of 5th to save wear on the transmission, not the motor. I think the trans is the weakest link when towing. 4th gear is direct drive 1/1 on your main shaft. 5th is on the counter shaft, so a lot more thrust forces and stress on your bearings.

 

I pull stuff all the time drive so your comfortable .

Then I tend to avoid Interstates if at all possible just something about the majority of the traffic running 20 to 30 mph faster that gets old to me.

After all it is your vehicle

 

It's always been my practice to stay out of overdrive and run the increased RPMs. The few times I thought I'd be ok towing in 5th with my '07 4cyl 5 spd, I ended up smelling clutch (even with a light load), after those few tries, I decided overdrive was NOT for towing. (period)

 

Lugging the engine down in rpms, was thought to create more engine wear. But in saying that: Over reving the engine can also do harm.

Try to keep the rpms in the safe range for engine. Some tachometers have marks on the tach, to guide you in this. I'm sure you heard of Red-Lining an engine; thus going past the recommended rpm range. Not a good thing to do either.