Locking out overdrive???

I run tow-haul all the time except when I get a 20 mile downhill where the engine can just idle along. It is better for a transmission as it doesn't slip and slipping can cause burning and burning can let the smoke out of your transmission which will smell awful and leave you on the side of the worst road you can get on.

Rather than running in S4, use Tow/Haul. Also, Tow/haul is inoperative anytime you are in manual select (S mode). Tow/haul will let the transmission use the overdrive gears anytime it is able to without lugging the engine.

On downgrades, I always use S mode and choose a gear that allows me to maintain the speed I choose with very little braking.

When I had my 2010 Tundra I always towed in S5 and tow haul mode. I live in a really hilly area and my truck was constantly going in and out of 5th and 6th. Also if you have tundra questions there is a Tundra forum that was really helpful for me, not saying this forum isn't helpful.

Try doing it both ways and keep track of your mileage. See if there is a fuel advantage to using OD. I bet there isn't but I've been wrong before.

Depends on your speed and your engines sweet spot. At 55mph or less, OD may not be the best gear choice.

bowler1 wrote:
This is somewhat a followup to my post about towing in the mountains. Consensus was that it was better to stay in a lower gear with higher rpms.

What about on the flats and more moderat grades?

My tundra has a s mode where you can limit the top gear. If i lock out 5th and 6th and keep it in fourth i never need to downshift unless on an extreme gradr, but it just seems that i must be burning a lot more fuel.

What do you recommend?

i think you will be able to answer your own question. if you know for sure its flat and moderate? still your working your tow vehicle harder towing. heat & trailer tire speed.
more about control than saving a few buck on fuel. its all part of towing.

the first time you take a wheeeeee ride off a mountain and smoke your breaks trying to get back under control.

you will under stand the wisdom in gearing down in the mountains.

trust me, gas is cheaper than warped rotors and break jobs. not to mention the safety factor on not having a run away vehicle.

As stated above, if the transmission is not excessively trying to change gears, you are fine to use overdrive. It the transmission starts to excessively change gears, lock out the overdrive.

I always stay in OD unless the trans begins to hunt for gears. Then I drop down 1 to 2 to 3 gears depending on the grade.

I wouldn't lock out 5th and 6th, but locking out 6th should be fine as it's a pretty high gear.

Reading up on the new 6-Speed it seems that tow/haul in S5 is preferred on flats.

My Tow Haul does that.