Silverado 1500---5.3 L Tow package

[davez]

I have always used TOW mode when pulling the 8000 lb Flagstaff. I am asking for opinions of NOT using the tow mode when on the interstates ( I- 81, I-78) that are essentially level ( but keeping an eye on the transmission temperature). The goal is to improve gas mileage from 11mpg

[DieselDrax]

Consider yourself lucky to get 11mpg. Disabling tow/haul won’t improve your fuel economy, I know some people think that higher RPMs mean lower fuel economy but that’s not how it works.

11mpg with an 8k TT is doing quite well.

[timfromma]

You should feel lucky that you get 11mpg. My last truck was a 1/2 ton gas and I typically got around 8mpg. My 3/4 ton diesel gets 12mpg.

[hondo]

I wouldn't do it. Even if you did get any better gas mileage it's not worth it verses the cost of a transmission. One time after refilling the gas tank I forgot to hit the tow/haul button. 10-15 minutes later I noticed it and the trans fluid temp was real high. I hit the button and the temp came down to normal. It definitely makes a difference with the trans fluid temp.

[Mr. Dan]

Originally Posted by hondo

I wouldn't do it. Even if you did get any better gas mileage it's not worth it verses the cost of a transmission. One time after refilling the gas tank I forgot to hit the tow/haul button. 10-15 minutes later I noticed it and the trans fluid temp was real high. I hit the button and the temp came down to normal. It definitely makes a difference with the trans fluid temp.

Your ‘03 Allison is a lot different from his ‘14 GM transmission. Tow/haul function has also changed in 11 years.

[Brewhedd]

I wouldn't do it, probably looking at engine and trans oils running at higher temps if your truck actually did shift into overdrive. You are towing, use tow mode.

[Lawrosa]

Tow haul does nothing really at highway speed. It will lock the torque converter in as fast as it can. Without TH you may generate more heat.

It will keep it out of OD until about 65 mph I believe. But IMO you should not entertain any OD. As in my trans there are only two clutch plates for OD. Youll burn them out quickly under an 8k load lugging it.

Tow in 4th or 5th.

Without TH youll be hunting for gears.. especially the OD gears.

I tow in 3rd. Its a 1;1 direct drive and soon as the TC locks. I dont even entertain 4th. As the 4l60e trans are about 3k plus labor...

TH mode also will downshif for grade assist and takes the alternator out of fuel saving mode and charge the camper batts at a higher voltage. The alternator is BCM controlled..

also with TH the line pressure is increased to keep the clutch plates together.

And of course holds gears longer.

[Kaadk]

I would love to have gotten 11 mpg. My 1/2 ton would only get between 8-9 mpg when towing a 6500-7000 lbs Flagstaff. I've only done one trip with the new 3/4 ton and fiver, but for that trip it came in around 8.6 mpg.

[howie70]

Originally Posted by hondo

I wouldn't do it. Even if you did get any better gas mileage it's not worth it verses the cost of a transmission. One time after refilling the gas tank I forgot to hit the tow/haul button. 10-15 minutes later I noticed it and the trans fluid temp was real high. I hit the button and the temp came down to normal. It definitely makes a difference with the trans fluid temp.

Originally Posted by Mr. Dan

Your ‘03 Allison is a lot different from his ‘14 GM transmission. Tow/haul function has also changed in 11 years.

So what is your recommendation to the OP, tow haul or no tow haul?

[SemperFi06]

Originally Posted by davez

I have always used TOW mode when pulling the 8000 lb Flagstaff. I am asking for opinions of NOT using the tow mode when on the interstates ( I- 81, I-78) that are essentially level ( but keeping an eye on the transmission temperature). The goal is to improve gas mileage from 11mpg

I have the same truck and never use it unless I’m in mountains. It’s removes overdrive and you’re gas mileage isn’t going to change IMO

[007matman]

I used tow/haul selectively. Problem is it uses the tranny to.slow down. While this is helpful in some situations it it not in others and causes the engine to rev really high. If I knew I was coming to a gradual stop and had plenty of room.to brake I'd turn it off.

Otherwise, I would always leave it on.

Congratulations on getting 11mpg.. my Esky pulling a 7400lb trailer would do about 5-6. Maybe 11mpg down hill :-)

[mopwr4me2003]

The function is there for a reason. Research went into it to design a truck tow tow so why would you not use it. To me it is just not worth will it or won’t it do this or break that. Really if you get 9mpg with it and 11 without it that’s only about 40-60 miles further but still the same amount of fuel to fill. But to each their own.

[JohnD10]

If I get 8 MPG when towing my 9900-pound 5'ver with a strong tailwind in my 2015 Chevy 2500HD gasser I feel good!

Generally between 5-7 MPG's when towing.

I always use tow haul mode...

Two issues I have with this truck...well, I have more, but these two are relevant to this topic:

1) I wish tow haul would stay on, even when you shut the truck off...

2) When in 4-wheel drive, there is no light on the dashboard to tell you that 4-wheel drive is engaged.

Once as I was hauling over Monarch Pass, Colorado I realized I had driven all the way from Denver in 4WD...with the trailer hooked up!

DOH!

[clutch]

On some trucks tow haul blocks out the highest gear. I have found that sometimes the higher gear doesn't save any fuel as you have to hold the throttle farther down to maintain the same speed. In my last truck, a Dodge diesel I found that the pyrometer showed higher temps when using the highest gear. Higher temps mean more fuel is being burned.

[hondo]

Originally Posted by Mr. Dan

Your ‘03 Allison is a lot different from his ‘14 GM transmission. Tow/haul function has also changed in 11 years.

Well Mr. Dan, I've worked in dealerships since 1973. If you or someone else doesn't want to use tow/haul mode when towing a TT or 5th wheel, be my guest. We love those kind of customers.

[ImTravis]

I always use the tow/haul mode when towing. It's what's recommended by GM, and I've had good luck with it so far.. helps saves your brakes when going downhill...

[Mr. Dan]

Originally Posted by howie70

So what is your recommendation to the OP, tow haul or no tow haul?

I use tow/haul anytime I’m towing or hauling.

[Mr. Dan]

Originally Posted by hondo

Well Mr. Dan, I've worked in dealerships since 1973. If you or someone else doesn't want to use tow/haul mode when towing a TT or 5th wheel, be my guest. We love those kind of customers.

Since you’ve worked at a dealership since 1973, you well know that an Allison behind a diesel is not the same as a non-Allison behind a gasser and that tow/haul software/hardware doesn’t work the same year to year.
I didn’t advise against tow/haul; I’m not sure how you got that; I use it anytime I tow anything or haul anything but I don’t use anecdotal information from a different transmission and software from 15 years back. My truck has 6 forward speeds - the top 2 are overdrive. T/H doesn’t lock out overdrive on mine as it did a few years ago on some trucks.

[MR.M]

here is my 2cents i'm sure it will ruffle some feathers . Tow/Haul or TH for short changes the shift points in transmissions . I have yet to come across an electronically controlled torque converter . one that will lock up by electronic controls . every torque converter I've come across has a preset lock-up set at a specific rpm . you can order torque converters that lock-up at different rpms . racers use them . on some manufactures TH will lock out overdrive and others it will not . once up to speed on flat highways running in top gear having TH on or off makes no difference unless your pulling hills then TH will down shift sooner .

IF you disagree please enlighten with any technical links you have to prove otherwise

[Waterops1]

Pulling our little Coachmen Viking (6542# gross) I keep in Tow/Haul Mode. Nice to just tap brakes and use tranny for braking. I have averaged 10-11 MPG in the last 400 miles display.