# Tow In O/d With Tow/haul Mode



## Ghosty (Jan 17, 2005)

So --

to make a long story short --

yesterday while hanging around the courthouse waiting to do some boring stuff -- I was sitting next to a gentlemen testifying in another case waiting to go in --

yada yada yada ... he turned out to be a senior technical design engineer from GM..

yada yada yada I asked him -- I'm have a 2005 Silverado w/ Tow Package 3.72 rear end and a 5.3L â€" and tow about a 6000 pound trailer â€¦ should I tow in O/D or 3rd...

his answer was

Tow in O/D..

He said that the computer on board senses transmission heat, idle, speed, engine temp, tach, etc etc and does all the adjustments -- that allot of folks think its better to tow in third but all that does is waste gas and has no better affect on the capabilities of the vehicle...

of course he could only vouch for the Chevy Silverado but i thought I would share that for all the 2005 Chevy Silverado owners..

I will tell you one thing that I found that dramatically made my truck tow better was adding:

1. Throttle Body Spacers
2. Big A** Air Cleaner
3. 3in Flowmaster exhaust

Night and Day difference -- where before at 60 and going up an incline it was searching for gears -- now it just stays in one and moves along -- plus my gas mileage for towing has jumped 3mpg...


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## HootBob (Apr 26, 2004)

Glad to hear you're getting 3 more mpg, Every little bit helps









Don


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## PDX_Doug (Nov 16, 2004)

That's good to hear, Ghosty.

It seems, as with so many things these days, advanced technology is re-writng the rule books, and the old hard and fast rules need a little re-examination. As you all know, I am very old school on this topic, but I am also open minded. For my part, I am going to take a much closer look at the Titan situation, and maybe even try a little O/D towing (in very controlled and closely monitored conditions), and see how it goes.

I still believe that the old rule of never towing in overdrive is going to be valid and appropriate for most, or if you have any questions or doubts about your vehicles capabilities. But for those with newer vehicles, it does seem that it is worth closer scrutiny before making any conclusions. I will also suggest, that anyone even considering taking part in this experiment, have a quality transmission temperature gauge, know how to read it, and watch it like a hawk.

Hmm... I wonder if this is what they call a 'sea change'?









Happy Trails,
Doug


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## Ghosty (Jan 17, 2005)

Yeah the GM guy told me that in O/D with Tow/Haul engaged the shift points were changed and that running uit in thrid while towing was actually detrimental to good fuel economy... and did nothing to "help" the transmission ...


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## Herbicidal (Aug 29, 2003)

From the Toyota perspective, I recently towed our Outback up I-5 north to Oregon. The first 2 1/2 hours of the drive is very flat. I have had a tranny temp gauge for over 2 years now. So, I'm cruising along with OD turned off and the engine is turning 3,000 rpm @ 62mph and seems to be happy all day long doing it. I checked the tranny temp and it's showing 165. Seems good to me. For grins, I go into OD. The rpm's drop to about 2,200 and slowly but surely the tranny temp gauge steadily climbed. When it hit 215 degrees, I took it out of OD and within 3 miles (all of this on flat ground) it went right back to 165.

So for me and my *Toyota*, no OD while towing.


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## old_tidefan (Nov 23, 2005)

Maybe the GM guy was one of those people that didn't like lawyers and was just trying to get you to burn up your tranny









Never know


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## Katrina (Dec 16, 2004)

Herbicidal said:


> From the Toyota perspective, I recently towed our Outback up I-5 north to Oregon. The first 2 1/2 hours of the drive is very flat. I have had a tranny temp gauge for over 2 years now. So, I'm cruising along with OD turned off and the engine is turning 3,000 rpm @ 62mph and seems to be happy all day long doing it. I checked the tranny temp and it's showing 165. Seems good to me. For grins, I go into OD. The rpm's drop to about 2,200 and slowly but surely the tranny temp gauge steadily climbed. When it hit 215 degrees, I took it out of OD and within 3 miles (all of this on flat ground) it went right back to 165.
> 
> So for me and my *Toyota*, no OD while towing.
> [snapback]127069[/snapback]​


In todays world of Computer controlled vehicles, I can see where the Toyota would need to stay out of OD and the Chevy would not AS LONG AS the tow/haul mode is engaged.


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## jfish21 (Feb 14, 2006)

This is being debated in another theard also 
I have a 01 2500hd 8.1 with the alison I tow in od tow/haul mode the tran temp never reaches above 185deg and never hunts for the proper gear.
and I'm pulling around 8500lbs.
the computer makes all adjustment needed
that the chevy and the alison trans


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## Ghosty (Jan 17, 2005)

Herbicidal said:


> From the Toyota perspective, I recently towed our Outback up I-5 north to Oregon. The first 2 1/2 hours of the drive is very flat. I have had a tranny temp gauge for over 2 years now. So, I'm cruising along with OD turned off and the engine is turning 3,000 rpm @ 62mph and seems to be happy all day long doing it. I checked the tranny temp and it's showing 165. Seems good to me. For grins, I go into OD. The rpm's drop to about 2,200 and slowly but surely the tranny temp gauge steadily climbed. When it hit 215 degrees, I took it out of OD and within 3 miles (all of this on flat ground) it went right back to 165.
> 
> So for me and my *Toyota*, no OD while towing.
> [snapback]127069[/snapback]​


But is 215 bad -- i don't know -- I mean -- where's the bad point -- what happens if 215 is just fine and all you're doing is burning more gas??? I just don't know..


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## Fire44 (Mar 6, 2005)

I don't know about Toyota but on my 2000 Suburban, the GM computer would turn on the check engine light after the transmission fluid had reached 266 for 10 mins.

I would also be interested in where he is measuring the transmission temp. My Suburban would run at 200 on flat land without the trailer (90+ degree day).

Gary


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## nascarcamper (Jan 27, 2005)

The best advice is read your manual and do what it says. Not all makes suggest the same thing. My truck has the tow haul feature but the manual says use it when towing "heavy" loads. My 28 BHS is not a heavy load for the truck. I've tried both ways and the only difference I see is it stays in lower gears longer when taking off from a dead stop which just annoys the you know what out of me.


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## PDX_Doug (Nov 16, 2004)

nascarcamper,

Staying in lower gears longer is what the Tow/Haul mode is all about, so I would not be annoyed at that.

It would be interesting to know what they consider a 'Heavy load'. The 28BHS may not be at your limits, but I would guess it definately qualifies as a heavy load.

Happy Trails,
Doug


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## Herbicidal (Aug 29, 2003)

Fire44 said:


> I don't know about Toyota but on my 2000 Suburban, the GM computer would turn on the check engine light after the transmission fluid had reached 266 for 10 mins.
> 
> I would also be interested in where he is measuring the transmission temp. My Suburban would run at 200 on flat land without the trailer (90+ degree day).
> 
> ...


I have a tranny temp light that I believe comes on @ 270 degrees after 10 minutes. However, I have never tested that.









I installed a sending unit after the tranny pan and before the fluid goes to the cooler. I recently bought a second tranny pan, had a threaded insert for a second sending unit welded welded to the new pan. Now I just need to swap pans, connect up the second unit to a switch so I can check temps in the pan and before the cooler. They should be virtually indentical. I was part of a discussion thread over on TundraSolutions about the best place for a tranny temp sending unit and it was ultimately decided that in the pan would give the best results. However, since I have a light on the dash for an overheated tranny, I wonder where Toyota placed their sensor? I probably should ask my Toyota mechanic buddy to track that down for me.

On our last towing day returning from Oregon, it was 103 in the Sac valley. With OD turned off and the AC blowing, the tranny temp showed 165 degrees. One other thing I did about 3 years ago was to upgrade the tranny cooler and install an additional in-line filter. The new cooler is at least 2x larger than stock so I'm sure that is helping with the overall cooling.


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## nascarcamper (Jan 27, 2005)

PDX_Doug said:


> nascarcamper,
> 
> Staying in lower gears longer is what the Tow/Haul mode is all about, so I would not be annoyed at that.
> 
> ...


I doubt it. The tow rating is enormous on that truck. No gear hunting with the tow haul off even in the NC mountains or interstate. No noticeable difference in fuel mileage either way. The Ford diesel mechanic told me I could stick to the 7500 mile oil change interval as long as I stayed under 3000 miles of towing so that tells me they don't consider it a heavy load. I know it's supposed to stay in gears longer in tow/haul but as I said it's annoying to me and creates higher rpms while accelerating which is probably more damaging than towing out of tow/haul. I just don't see any advantage in using with my tt.


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## PDX_Doug (Nov 16, 2004)

OK!









Happy Trails,
Doug


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## Travelers (Apr 6, 2006)

Just returned from a 200 mile week-end trip and I just left it in OD and even though I didn't need it I left the tow/haul on. Tranny temp never went over 180 degrees and it kicked down to 3rd twice on a couple of steep hills.

I did notice that with the tow/haul off the front end would pogo more so I looked in the owners manual and sure enough, with tow/haul on the GM Autoride system controls the front shocks more to reduce the bounce - or pogo effect. So, for you folks with Autoride - keep tow/haul on for a smoother ride.


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