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Open Roads Forum  >  Travel Trailers  >  General Q&A

 > MPG and RPM Question for Chevy truck-New RVers

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afidel

Cleveland

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Posted: 04/02/19 10:48pm Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:

Ralph Cramden wrote:

Shawfamily6 wrote:

It was pretty windy and raining that day. The next day we got closer to 7.5. I have seen a few of you mention different gears. Should we be pulling in something other than automatic? I think I might be confused. I know you can take it out of automatic, is that what we should do and put it in a different gear? If so, what gear do you recommend? Sorry if that is a silly question! Thanks for all the help!


If your not in rolling hill country or stop and go traffic, with a 7500 lb trailer behind a 6.0 GM 2500 take it out of tow/haul. Don't use the tow/haul on an interstate or other 4 lane highway. Its not needed and is probably what shot your mpg in the foot. Leave it in D and drive it. When you get in hill country or stop and go traffic kick in the tow /haul, take it out of D, and shift manually. Drive it like you stole it. Wind it up to 4500/5000 rpm. It really sounds good up there.


The owners manual will tell you what conditions to use the tow / haul button and trying to get the most mpg is not one of them. It won't hurt the truck whether or not you use the tow / haul button, or if you have it in D or shift it manually with the rocker switch. Those trucks are made to tow and haul. 7500 lbs behind one is an easy day for the truck.


Hmm.. I guess I don't think I would ever like to own a Chevy if Tow/Haul "affects" mileage..

I am thinking Chevy follows a similar pattern like Ford, Tow/Haul mode MODIFIES the shifting pattern/strategy to TAKE BETTER ADVANTAGE of the engines torque. This often means holding a gear a bit longer to get into the sweet spot on the RPM essentially delaying upshift or downshift.

On Ford, tow/haul ALSO adds in AUTOMATIC DOWNSHIFT strategy for better control of your vehicle speed when descending hills or even stopping at traffic lights or even sudden maneuvers which require faster stopping. It assists you..

If GMs does not do that then why even put that feature on the vehicle???

I would suggest READING THE MANUAL on what Tow/haul does for YOUR VEHICLE, then FOLLOW THE MANUAL rather than arm chair QBs behind the keyboard..

I enable Tow/Haul EVERY TIME I hitch up or even put a huge load of cement blocks in the back of my Ford, my Tow/haul has never hurt my mileage, in fact it seems to HELP the mileage while towing or hauling..


The other thing that tow/haul does is engage the torque converter at a lower RPM which leads to lower transmission temperatures, that can be very important in some situations.


2017 KZ Sportsmen Classic 181BH
2015 GMC 1500 Sierra 4x4 5.3 3.42 long bed
E2 WDH


JIMNLIN

Oklahoma

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Posted: 04/03/19 08:54am Link  |  Quote  |  Print  |  Notify Moderator

Shawfamily6 wrote:

It was pretty windy and raining that day. The next day we got closer to 7.5. I have seen a few of you mention different gears. Should we be pulling in something other than automatic? I think I might be confused. I know you can take it out of automatic, is that what we should do and put it in a different gear? If so, what gear do you recommend? Sorry if that is a silly question! Thanks for all the help!

I use the manual mode on the wifes 6L80E tranny. I've also drive manual shift trannies in 3/4 and one ton trucks so I understand which gear needs to be selected for . I can also get better mpg in manual mode empty or pulling a 10k trailer with the 6L80E.
If your not adapt at proper gears for the job I would recommend T/H mode.
Now if your traveling in the mountains you will have to learn to use manual mode so you can choose a lower gear to keep RPMs up (3k-4k rpm) to slow the truck/trailer on steep downgrades.

Family6...pay attention to other 2500 GM 6.0 engine owners as the Ford or Dodge/Ram tranny may not have the same shifting parameters.


"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers

'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
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BarabooBob

Baraboo, WI

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Posted: 04/03/19 10:14am Link  |  Quote  |  Print  |  Notify Moderator

I drive a 2011 F150 w/3.5 EB 6 sp. If I have the trailer on the back, I am in tow/haul. My truck will downshift to maintain cruise control speed whether in tow or not.
I use my cruise control, set at 55-60 on state roads and get about 11-12 mpg. If I run 65 mph, I get 8-9 mpg. I am retired and in no hurry to get anywhere, I go 55-60.
I do my own shifting in the mountains, going up and down.


Bob & Dawn Married 32 years
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Shawfamily6

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Posted: 04/03/19 07:25pm Link  |  Quote  |  Print  |  Notify Moderator

I appreciate all of the responses! It sounds like we will just have to do some experimenting and see what works the best for us! Thanks everyone ??

APT

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Posted: 04/05/19 06:50pm Link  |  Quote  |  Print  |  Notify Moderator

We have a Suburban with same engine and transmission, but 3.73 gears. I tow at 70mph and get 8mpg. Sometimes a little less, sometimes a little more. I use tow/haul mode on the transmission and I like to use M5 to limit to gear to 5th. I cannot hold 6th gear very long and ends up downshifting to 5th, or 4th when it loses speed. You should use less fuel in 5th than 6th when towing.

That truck can turn 3000rpm all day long towing that trailer.


A & A parents of DD 2005, DS1 2007, DS2 2009
2011 Suburban 2500 6.0L 3.73 pulling 2011 Heartland North Trail 28BRS
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Tacky

Shaiwassee County Michigan

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Posted: 04/07/19 03:47pm Link  |  Quote  |  Print  |  Notify Moderator

Shawfamily6 wrote:

Thanks for all of your responses! My husband has informed me that we have a 2500 HD, not a ½ ton ??. We have a vortex 6.0L V8 gas engine, 6 speed with a 410 rear axle. We have 20 inch wheels with a GVW of 9500lbs. It doesn’t have OD, but has a tow haul button. Do most people use this when pulling their TT on the highway? I know my husband uses it when pulling his enclosed trailer in town. We have been driving about 63-65 MPH, so maybe we need to keep it around 60. I really appreciate all of your help! We plan on traveling quite a bit this summer, and with 4 kids we want to save where we can. So if we need to drive 60, that’s what we will do!


Hi Shawfamily6. I do know a lot about GM trucks, I used to work for their Technical Assistance Center. That 2500, with the 6.0 V8 has a lot of pull, but is not known for good gas mileage. The 4:10 axle gives you even more pull, but less mileage. Still, 6 mpg is pretty low. Yes, your 6 speed transmission does have OD, I think both 5th and 6th gears are overdrive gears. Probably you don't get into 6th while towing with tow/haul on. What I would suggest, is to keep speed a little lower, and try putting the transmission into manual and put it in probably 5th gear, and see how that does. Tow/haul is nice, and I use it most of the time on my truck, but it seems more concerned with giving you maximum tow power, and less concerned with mileage. Speed is the enemy of fuel mileage. I can tow at 70, but the mileage is lousy. Way better at 60-63 mph. That said, it is shocking how poor the fuel mileage is when towing a travel trailer.


Shiawassee County, Michigan

Gdetrailer

PA

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Posted: 04/07/19 05:15pm Link  |  Quote  |  Print  |  Notify Moderator

My comments below in red..

Tacky wrote:



Hi Shawfamily6. I do know a lot about GM trucks, I used to work for their Technical Assistance Center. That 2500, with the 6.0 V8 has a lot of pull, but is not known for good gas mileage. The 4:10 axle gives you even more pull, but less mileage. Still, 6 mpg is pretty low.

I concur, decent and enough engine to get the job done and 4:10 axle does help the cause for towing although can rob you of some mileage if you are routinely stomping the go pedal when towing.

Yes, your 6 speed transmission does have OD, I think both 5th and 6th gears are overdrive gears. Probably you don't get into 6th while towing with tow/haul on.

Technically, the manufacturers DO NOT CONSIDER 5 and 6 as "OVERDRIVE" in a 6 speed transmission, yes there IS SOME extra "gearing ratio" ABOVE 1:1 but in reality not all that much to write home about.. That extra gearing above 1:1 SHOULD NOT be a problem for the 6.0 EVEN WHEN TOWING!!!, Especially when combined with 4:10 axle, this is not a 5.3 engine nor is it a 6 cylinder..

What I would suggest, is to keep speed a little lower, and try putting the transmission into manual and put it in probably 5th gear, and see how that does.

Speed LOWER, YES, however that does not seem to be the issue here, if I remember correctly OP IS towing WELL UNDER 70 MPH (55-65?)..

Transmission in "manual"??? HECK NO, that IS one of the DUMBEST MYTHS that just keeps getting brought back from the dead by folks who just won't give up the old manual "handshaker is better" mentality.

To that mentality I say GET OVER IT, manual transmissions have gone out of existence like the dinosaurs, 8 track tapes, cassette tapes, analog TV and many other old out of date things that used to be the way of life.

The truth is, the last few years that real manual transmissions were offered in trucks the manufacturers DERATED the towing capacity.. Automatic transmissions were rated higher towing capacity and they are here to stay.

The manufacturers ARE SMARTER than most folks who feel they are better shifting than how the manufacturers programed the automatics to shift. These newer transmissions can detect and adapt faster to changing conditions and have one big advantage of being directly fed information on the engines operating condition..

Your "manual" button is only a MAKE BELIEVE "manual", back in the 60's and 70's it would be actually referred to as a "semi automatic" mode (automatic transmission without a valve body to automatically shift and no manual clutch). Engine computer is not going to let you over rev or do something that will damage the transmission or engine, it will throttle your engine back.

Put the stupid thing IN DRIVE and forget about the manual button.


Tow/haul is nice, and I use it most of the time on my truck, but it seems more concerned with giving you maximum tow power, and less concerned with mileage.

Tow/haul should be concerned with maximizing your tow power, it basically is running your engine inside the max power band which puts the absolute max of your EFFICIENCY down to the road surface. More power gets to the road the less wasted power elsewhere.. In doing so it CAN actually IMPROVE your mileage over not running Tow/haul.

As mentioned before, Tow/haul alters the shifting strategy, it does also alter the torque converter lockup strategy, these ARE EXTREMELY GOOD THINGS and you are basically poo-pooing it..

Tow/Haul also enables automatic hill decent downshifting, this feature in it's self should be something that everyone is taking advantage of. You do not have to do anything and it will automatically downshift down hill so you don't need to stand on your brakes.. If you feel you need to slow down more, just tap the brake pedal and it downshifts to the next lower gear.. Much nicer than having to manually downshift and much safer.

POWER EFFICIENCY IS KEY TO BEST MILEAGE, LESS LOST POWER DUE TO HEATING UP YOUR TRANSMISSION AND TORQUE CONVERTER.


Speed is the enemy of fuel mileage.

OP ISN'T SPEEDING so why keep bring this up?

However, if OP is trying to stomp on it at every stop light they WILL take a massive hit to the mileage.. Nice and easy on rolling from stop lights will vastly improve gas mileage.. Forcing it to get up to speed from a stop light just vacuums out the gas tank..

Pretend there is a egg between your foot and gas pedal, you WILL see a vast improvement in mileage.. OP is not towing a popup anymore in this case so it takes time to get back to speed, takes some time to adapt to the bigger and heavier trailer in tow. What the OP did when towing a popup, no longer applies to a big, heavy cement block.


I can tow at 70, but the mileage is lousy. Way better at 60-63 mph. That said, it is shocking how poor the fuel mileage is when towing a travel trailer.

My mileage as I mentioned is 9.5-10.1 hand calculated and have no issue getting that running 70 MPH speed limits. Main reason I do get decent mileage is I use a LIGHT foot on the go pedal when getting up to speed.



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