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-   -   Chevy/GMC 6.0L Help Plz? Fuel Consumption (https://www.airforums.com/forums/f463/chevy-gmc-6-0l-help-plz-fuel-consumption-132401.html)

FishinHatteras 03-16-2015 08:28 AM

Chevy/GMC 6.0L Help Plz? Fuel Consumption
 
Fellow AS'ers,
I wanted to ask fellow folks what they are getting mpg wise when towing their rig with the 6.0L? I have never checked what kind of gas mileage I was getting while towing but decided to check it y-day. In a 92.8 mile span of use, I managed to get a lousy 8.5 MPG. That just seems too low. I was expecting closer to ten, more like 11.

My specifics: All tires inflated on the tow vehicle to 60lbs. I have not taken the time to check the tire pressure on the TT in about three weeks. That was pretty stupid on my part, and I should have checked it before we left. Going to go check them right now. I had no water in my tank, and hardly anything in the TV. Wife & two dogs, with minimal cargo besides my tool box & socket set. TT is a 28' Int'l Ocean Breeze. Tow vehicle is a 2012 Chevy 2500 Crew Cab with a camper top.

I have several questions:

Did I drive far enough to even GET a good average? We were coming back from Myrtle Beach, so we were steadily increasing above sea level.

What are you guys getting towing a similar rig? I have the 3.73 rear thankfully. I was trying to stay just under 70mph, and keep it in O/D as long as possible. I was trying not to fall below 65mph, unless on a steep hill. I wasn't getting into the throttle, but I wasn't trying to baby it either.

The only engine modification I have made was installing a K&N air filter. All else is stock.
What can I do to increase that MPG w/o spending a great deal of $?

We are trip planning to Phoenix, AZ this May, with stops in UT, CO & others. I am trying to determine what my fuel expenses are going to be. I was figuring around 11 MPG, but this sure increase the bill significantly.

Thank you for taking the time to respond to my questions.
Gavin

warrenl55 03-16-2015 08:50 AM

11 mpg avg. 2014 Ram 2500 with 6.4 Hemi gas 3:73 rear 4wd. Pulling 2014 27FB full load in bed and water tank full. About 6000 miles total in October. California via I40 to Blue Ridge parkway to home.

field & stream 03-16-2015 08:53 AM

Hi -- Here's my experience with a 2001 Yukon Denali, 3.73 rear, towing a 23' trailer (4,500 lbs empty) :

> drove from CA to CO to pick it up and got 18 mpg
> drove it home and got 11.5

Here's my opinion:

> With your trailer's empty weight of almost 6,000 lbs, your observed mpg is not surprising
> the difference in gas mileage between 60 and 70 mpg is significant.
> there are many other advantages to towing closer to 60 than 70

moosetags 03-16-2015 09:02 AM

We have towed our Airstreams with two different Suburban 2500's. Both of these Suburbans had the 6.0 liter gasoline engine. Between the two they had over 100,000 miles of Airstream towing. Our 2005 Safari 25FB weighed 7,400#. These Suburbans were an '04 and an '05 and had the four speed transmission and 3.73 rear.

Our long term gas mileage experience has been between 8.8 and 10.1 mpg. We usually travel on the highway at around 65 mph. We have always found that gas mileage while pulling a large trailer is very dependent upon prevailing winds and road grades.

I think that a 93 mile run is hardly enough to make any real mileage determination. A better run to get a real average mpg would be 5,000 miles.

Brian

handn 03-16-2015 09:33 AM

I think your fuel mileage is in the range of what to expect. I got similar mpg with a boxier trailer and a gas tow rig. With a smaller trailer and a 7.3 Powerstroke Excursion, I am consistently between 11.5 and 12.5. Diesels get about 20% better mileage than gas.
My driving habits are similar to yours--65 70 mph.
As Moosetags suggests, you could up your mileage by driving under 60.
There is real mpg and internet mpg, the latter is 30% to 40% higher but very difficult to achieve in the real world. Perhaps it is achievable going downhill with a tailwind.
Wind resistance is a big factor. I got 14 mpg for a 200 mile stretch with a significant tail wind when outrunning a storm and 10 mpg when busting into a big headwind.
I am always looking for a silver bullet to increase mileage. Stanadyne (a diesel additive) seems to give me 5% better mileage, but the cost of the product equals the amount of savings.
I did notice a boost of at least 5% when I switched tires from an offroad tread tire to a Michelin M&S.
The bottom line is that it takes a lot of energy to move your truck and heavy trailer down the road, but think of all the money you are saving on meals not eaten out and motels not stayed in.

ckottum 03-16-2015 09:57 AM

Use the tow/haul mode and set the cruise control at 60 mph, relax and enjoy the drive. If the transmission wants to shift up/down frequently, as it most probably will do in headwind and up even slight grades, manually shift down a gear as needed to minimize it and leave it there.

cheryl k

cwf 03-16-2015 11:02 AM

My friend has 2012 2500 6.0 gasoline. Tows a SOB with square front. His mileage about 10.5-11.0 here in Texas Hill Country. Worse on windy days. Speeds similar. Sounds like you are not unique on mpg.

spclkaz 03-16-2015 11:36 AM

I've towed my 94 30 ft. Excella FK around for about ten years with a 99 GMC 2500 with a 6.oL gasoline engine out here in AZ and the rest of the West. The trailer weighs over 9,000lbs and I usually tow with empty tanks if I know I can get water when I get where I am going... I keep very careful mileage records... I always engage the tow/haul mode... on the freeways I set the cruise to about 62 or so... I consistently get around 9.5 -11 MPG when towing... that's over a 15 year period...

Seabloom 03-16-2015 11:36 AM

Hi Fishin,

I have a 1976 Overlander (6200 lbs empty) and tow with a 2012 GMC crew cab 6.0l with 4x4, also the 3.73 gears. While towing my trailer I average as other users have indicated about 9-11 mpg. For sure every mph above 60 the mileage gets increasingly worse. I used to have a 9ft long camper in the back of the truck which only weighed 2000 lbs. At 60 mpg I could hold about 12 mpg, at 70 mph I was down to 8.5 mpg. For me the interstates are the real killer, I just want to get there but it is a cost vs patience exercise.

murreywalker 03-16-2015 11:45 AM

Quote:

Originally Posted by moosetags (Post 1593997)
We have towed our Airstreams with two different Suburban 2500's. Both of these Suburbans had the 6.0 liter gasoline engine. Between the two they had over 100,000 miles of Airstream towing. Our 2005 Safari 25FB weighed 7,400#. These Suburbans were an '04 and an '05 and had the four speed transmission and 3.73 rear.

Our long term gas mileage experience has been between 8.8 and 10.1 mpg. We usually travel on the highway at around 65 mph. We have always found that gas mileage while pulling a large trailer is very dependent upon prevailing winds and road grades.

I think that a 93 mile run is hardly enough to make any real mileage determination. A better run to get a real average mpg would be 5,000 miles.

Brian

I will offer the same as Brian.

I get between 8.5 - 11.5 depending on terrain and an average speed of about 65 mph in our Suburban 2500 (2013).

I suspect a 6.0 is a 6.0 is a 6.0

Jack46 03-16-2015 11:49 AM

We previously had a 2008 Suburban 2500 that came with the stock 6.0L, but we added a 4.10 rear end. We would get 9-10 hauling our 30' FC (a lot less in the mountains).

Rascal0729 03-16-2015 11:51 AM

I tow with a 2006 4500 Topkick Dura Max Diesel get 5.5 mpg

KWN306 03-16-2015 12:04 PM

I have learned on my 2000 Dodge 2500 4x4 with a 3.73 rear that the sweet spot is between 60 to 62 mph, will get me about 14.5 mpg. If I am hammering it; it will go down to 9 - 10 mpg and that is with a camper shell on the bed of the truck, it drops 2 mpg without the camper shell.

Slow down and smell the roses and you mileage will increase greatly.

jcanavera 03-16-2015 12:15 PM

I've got a 6 liter 4.10 axle in my 3/4 ton GMC van. We do between 11-13 mpg towing our 30' slide. The 4.10 allows us to do most of our towing in OD, except when we get into hilly terrain. In those cases we manually drop down a gear as we assend the hills.

Jack

EarlM 03-16-2015 12:18 PM

I also would recommend leaving it in tow haul mode when towing and don't worry about gas mileage there are too many variables, ethanol v/s no ethanol, 87 grade fuel vs's higher octanes.

enjoy the ride the difference is not significant. just spend your kids inheritance and have fun

I like to run 70 mph

earl

johncook 03-16-2015 12:20 PM

11 is about what to expect at 60 MPH
I have a silverado 2500 HD with the 6.0

1Boyscout 03-16-2015 03:14 PM

Quote:

Originally Posted by FishinHatteras (Post 1593982)
Fellow AS'ers,
I wanted to ask fellow folks what they are getting mpg wise when towing their rig with the 6.0L? I have never checked what kind of gas mileage I was getting while towing but decided to check it y-day. In a 92.8 mile span of use, I managed to get a lousy 8.5 MPG. That just seems too low. I was expecting closer to ten, more like 11.

My specifics: All tires inflated on the tow vehicle to 60lbs. I have not taken the time to check the tire pressure on the TT in about three weeks. That was pretty stupid on my part, and I should have checked it before we left. Going to go check them right now. I had no water in my tank, and hardly anything in the TV. Wife & two dogs, with minimal cargo besides my tool box & socket set. TT is a 28' Int'l Ocean Breeze. Tow vehicle is a 2012 Chevy 2500 Crew Cab with a camper top.

I have several questions:

Did I drive far enough to even GET a good average? We were coming back from Myrtle Beach, so we were steadily increasing above sea level.

What are you guys getting towing a similar rig? I have the 3.73 rear thankfully. I was trying to stay just under 70mph, and keep it in O/D as long as possible. I was trying not to fall below 65mph, unless on a steep hill. I wasn't getting into the throttle, but I wasn't trying to baby it either.

The only engine modification I have made was installing a K&N air filter. All else is stock.
What can I do to increase that MPG w/o spending a great deal of $?

We are trip planning to Phoenix, AZ this May, with stops in UT, CO & others. I am trying to determine what my fuel expenses are going to be. I was figuring around 11 MPG, but this sure increase the bill significantly.

Thank you for taking the time to respond to my questions.
Gavin

You did not say what your TT weighs. I pulled a 34' TT, 8200lbs, 62 to 65 mph, with a 2003 1500HD, 6L. I averaged 8.5 to 9.6. A K&N Filter did not help mine any. I bought the truck new, I use it most for towing. It only has 33k miles now.

The only way I found to help MPG is to park it.

dannydimitt 03-16-2015 03:56 PM

Keep it out of overdrive and don't get over 60 and SHAZAM ! you just might get that elusive 11

larryglarson 03-16-2015 04:52 PM

I have a 2014 Silverado 5.3 with 3.09 or so high speed rear end and pull a 2014 30' Classic. I do not use Tow Haul and drive 55 to 60. On a 5,000 mile trip from Iowa to the Pacific NW I got 11.5. Yes, it shifts more and is slower up the hills, but I like the mileage.

phbarnhart 03-16-2015 05:09 PM

Used to tow with a 2012 2500 Suburban. Your numbers seem about right given your speed and elevation change. The way that vehicle is geared, there's a huge difference between 60 and 70mph.

bwoodtx 03-16-2015 05:54 PM

I have an '09 2500HD/3.73 and I am towing a '97 Excella. Trailer weighs in at around 7900# I avg about 8.5-10.5 depending on conditions. I leave it in tow/haul and run about 60-65.

My toughts are that you don't buy the 6.0L for the fuel mileage, you buy it for the torque. I pulled a friends '54 Cruiser and avg 11.5-12.

NavyCorpsman 03-16-2015 06:53 PM

Along with the K&N, Royal Purple HPS Motor oil and Lucas fuel conditioner. It will give you about 1.8 to 2.5 more mpg. The lucas fuel additive is cheaper by the gallon(around 30). I prefill my own 1/2 pint bottles for use during refills. Love the stuff.
Try it once and see for yourself.

r carl 03-16-2015 07:26 PM

Quote:

Originally Posted by FishinHatteras (Post 1593982)
Fellow AS'ers,
I wanted to ask fellow folks what they are getting mpg wise when towing their rig with the 6.0L? I have never checked what kind of gas mileage I was getting while towing but decided to check it y-day. In a 92.8 mile span of use, I managed to get a lousy 8.5 MPG. That just seems too low. I was expecting closer to ten, more like 11.

Gavin

I have a 2500HD with the 6.0 and 4:11 rear. When I bought the truck my research showed people were getting better mileage with the 4:11.
I will lose 1 mile per gal for every 5mph over 55mph I drive. Also I will lose 1mpg if I use 10% ethanol. You wont gain anything if you use premium gas as the 6.0 is a low compression engine. Driving into a headwind will also kill your mileage. Use high quality lubricants in your diffs, transfer case, trans, and engine.

chaseav 03-16-2015 09:04 PM

I drive a 2007 Chevy Avalanche (1500) 2wd with 5.3L and 3.73. I am a pilot so I am constantly monitoring anything that can be monitored and in this case, fuel burn and trans temp are about it. When I first got the AS back in Dec, I was shocked to see my truck go from a highway average of 20 mpg all the way down to more like 8.5 once hitched. This terrified me. Since then I've towed 2500 miles and much to my surprise the fuel economy has steadily increased to where I now average 11 mpg. * I live in the south where it's mostly flat.

Nothing about anything to do with my setup has changed at all over this time except the total weight of the stuff we bring with has gone up. Something that should have the opposite effect. The fuel economy does not seem to change if I drop down below 65 nor does it seem to go down if I go over 70... I've never pushed it though to find out.

I'm very happy with my TV and Airstream's towing capabilities with one exception... in hot weather, stop and go traffic the trans temp gets up there to 210 degrees. The manual says 180-205 is normal operating but it give no other limitations. Should be interesting to see how the setup does over the mountains this summer!

n2916s 03-16-2015 09:21 PM

Fundamentally, it takes "x" amount of energy (btu's) to move your basic Airstream through the air and down the road. A little more for bigger, wider and a little less for shorter, narrower. Some engine/transmission combo's are a little bit more efficient than others and, of course, diesel has more btu's per gallon than gasoline.

Still, it takes more or less the same energy. So, if you surveyed all who tow, I'd be willing to bet that, long term and on average, most of us driving gassers are averaging 10-12 miles per gallon.

If you budget for that, you will seldom be cast into despair and may occasionally be delightfully surprised.

Mike

Sodbust 03-17-2015 06:03 AM

Our 5.7L Dodge does real well at 13.8 to 14mpg running flat ground with no or little wind at 60 pulling our Overlander.. But throw a 25mph corner wind at us and push it up to 68mph it can drop down to 11mpg in a heart beat..

Now here is my beef.. We have a well worn out (800.000 miles) 94 KW semi,, pulling a 42 foot grain trailer.. Several years ago I was pulling dry fertilizer out of Tulsa Ok.. 79,500 lbs total weight.. It was a nice day with little traffic. I just idled along at 50 to 58mph and made a 550 mile trip at 9.8mpg.. Never let the turbo boost go over 10lbs and roller coasted the hills as much as possible. I understand we are not matching up apples to apples but that rig is huge in relation to our A$..
By relation to profile and weight,, our TV should see 28mpg all the time..
Sodbust

dannydimitt 03-17-2015 07:13 AM

Quote:

Originally Posted by Sodbust (Post 1594487)
Our 5.7L Dodge does real well at 13.8 to 14mpg running flat ground with no or little wind at 60 pulling our Overlander.. But throw a 25mph corner wind at us and push it up to 68mph it can drop down to 11mpg in a heart beat..

Now here is my beef.. We have a well worn out (800.000 miles) 94 KW semi,, pulling a 42 foot grain trailer.. Several years ago I was pulling dry fertilizer out of Tulsa Ok.. 79,500 lbs total weight.. It was a nice day with little traffic. I just idled along at 50 to 58mph and made a 550 mile trip at 9.8mpg.. Never let the turbo boost go over 10lbs and roller coasted the hills as much as possible. I understand we are not matching up apples to apples but that rig is huge in relation to our A$..
By relation to profile and weight,, our TV should see 28mpg all the time..
Sodbust

Thanks for the input , I presume you have one of those conventional KW tractors with the sloped nose front end . When those first showed up I thought they were terribly ugly , but after driving a few of em and comparing them to the old 68 cab over KW with a 335 Cummins inline 6 and a 13 spd I broke out in , that ugly front end does help with wind resistance . The old 335 would get about 5 mpg in the mountains of Wyoming and Utah pulling a float and grossing a bit less than 80,000 . And would hardly do any better running empty !
Much the same for our Dodge 2500 with a 5.9 Cummins inline 6 with a 5 spd overdrive on the back of it . It gets 14 to 15 mpg pulling the AS with all the usual stuff loaded and fresh water tanks full . And only a couple of miles better running unhitched with no load at all.
Weight has much less of an impact on the MPG of a long stroke high compression diesel engine with a manual transmission than it does on a low compression , short stroke , gasoline engine coupled to an automatic transmission .
We used to pull the 66 AS with a 1971 International Travelall with a 393 V-8 coupled to a Chrysler 727 slush box with a 4.10 rear end , back when the speed limit was 55 nationwide and got between 5 to 8 MPG.
All these modern computer controlled gadgets that are on newer engines have defiantly helped with the mileage and power , but at the heart of the engine is still a low compression reciprocating piston gasoline engine .

J. Morgan 03-17-2015 08:45 AM

Here is my approximate experience, 08 Silverado 5.3L, neutral wind, etc.

60 MPH 11 to 12 MPG
65 MPH 10 to 11 MPG
70 MPH 9 to 10 MPG
75 MPH 8 to 9 MPG

My other TV 04 Tahoe 5.3, is the same less about 1/2 MPG.

Driving habits come into play a lot. I try to hold my travel gear with minimal downshifting, modern cruise control sucks while traveling in hilly terrain, it drives me nuts and wastes gas.

My goal is to NEVER allow a downshift above 70, the cruise sucks at that.



1/2 Ton 4WD Truck, 72 Sovereign Hensley Arrow

chaseav 03-18-2015 06:11 AM

Quote:

Originally Posted by J. Morgan (Post 1594531)
modern cruise control sucks while traveling in hilly terrain, it drives me nuts and wastes gas.


I emphatically agree. Was really surprised how "stupid" it is and disappointed that it's almost unusable. It makes long trips even longer. I've been very surprised how mentally drained I am when I get to a destination after towing.

KJRitchie 03-18-2015 09:15 AM

I only use cruise control on flat stretches just long enough to move my right leg around and stretch it then its back to manual driving.

Kelvin

Ridgerunner3 03-18-2015 02:30 PM

I have a 2002 Safari 25. I have owned a 2010, 2013, & 2015 Chevy crew cab 2500 with 6.0. 3.73 rear end until 2015. 2015 has a 4.10. My normal average on trips in excess to 1000 miles is 8.5 mpg. Short trips will vary some.


Sent from my iPhone using Airstream Forums

jcanavera 03-18-2015 04:16 PM

Quote:

Originally Posted by chaseav (Post 1594381)
I drive a 2007 Chevy Avalanche (1500) 2wd with 5.3L and 3.73. I am a pilot so I am constantly monitoring anything that can be monitored and in this case, fuel burn and trans temp are about it. When I first got the AS back in Dec, I was shocked to see my truck go from a highway average of 20 mpg all the way down to more like 8.5 once hitched. This terrified me.!

Not a total surprise. I used to tow a 6,000 lb 27' Safari with a Chevy half ton van. 5.7 liters with a 3.73 axle. Tow vehicle was not rated to tow in OD so I towed in 3rd. Mileage was between 11-13 mpg at 60 mph. Considering I went to a 3/4 ton GMC van with a 6 liter gas 4.10 axle and now pull a 30' Classic slide that weighs about 8,600+ lbs (depending upon how much fresh water I pull). That vehicle does the same 11-13 mpg. I attribute that to the fact that the transmission on this van is rated to tow with OD (as long as it isn't hunting).

The big difference however is solo city driving. That half ton did about 17-18 mpg where my 3/4 ton is still 11-13 mpg. I pretty much attribute the betterment with the half ton is the axle and OD driving.

Jack

chaseav 03-18-2015 06:36 PM

What I love the most is driving away once the trailer is unhitched. The truck thinks it's a Corvette and feel like I'm driving one.


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