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View Full Version : GM 6.0 Fuel Milage - Be honest!!!


procut
10-15-2010, 08:57 PM
I have an '06 2500HD that I've owned for about 3 yrs. I like the truck, but the milage is so bad, I can hardly stand it. It is an '06 Reg. cab, 6.0 gas, auto, 4.10 axle. Currently has 62,000 miles. Pulling my mowing trailer that weighs about 4500# it gets maybe 8.5 mpg. Pullingmy dump trailer, milage drops another mile per gallon to about 7-7.5. I have new michelen tires with proper inflation, and a K&N filter. The truck is not driven with a lead foot, and has minimal idle time.

Just curoius what other owners are expirienceing for milage with these trucks.

4 seasons lawn&land
10-15-2010, 09:40 PM
13 highway. 7-8 pulling the loaded dump trailer. 9-10 towing the alum enclosed 1 mower. Okay with me. We gotta tow stuff, whataya gonna do?

djagusch
10-15-2010, 09:48 PM
13 highway. 7-8 pulling the loaded dump trailer. 9-10 towing the alum enclosed 1 mower. Okay with me. We gotta tow stuff, whataya gonna do?

That is what my 09 gets for mpg. I just got an 05 also I'm guessing it will get alittle worse with the 4sp tranny.
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4 seasons lawn&land
10-15-2010, 10:04 PM
yup mine is 6 speed too

Brad Ent
10-15-2010, 10:18 PM
01 w/133K 10-12 MPG

TLS
10-15-2010, 10:35 PM
Thats what they get.

GM's have a very aggressive throttle plate to pedal ratio. Tip in is very aggressive. If you baby it off the line, it will improve.

Remember, you also have a LARGE powerband with the LS engine. From 2K to almost 6K your making great power. With the RPM's come more fuel. The 350's of yesteryear ran out of breath at 4500 rpm's. Bog the old 350's down....downshift, and they were almost instantly out of their power band. Todays trucks with the 4 and 6 speed trans put you in the sweet spot at each shift.

Runner
10-15-2010, 11:10 PM
I am wanting one of these trucks so bad, but I know that will be a price to pay. I want to find around a 2000 3/4 ton HD type with a plow for around 6 grand, or so. I've seen a few nice ones occasionally, and hope I come across one in a few months when I'm ready to make a purchase.

TLS
10-15-2010, 11:28 PM
Runner,

2000's were only LD 2500's

You really should be looking for a 2004 or newer (they changed body electronics in 2004)

procut
10-15-2010, 11:48 PM
Well I guess I'm not alone then. Mine has the old 4sp tranny. Apparently the new 6 speed doesn't make that much differance then. No one else posted what back axle they have. I still think that you sacrifice 1-2 MPG with the 4.10 vs. the 3.73. Anyone else?

TLS
10-15-2010, 11:53 PM
3.73 wasn't an option with 4spd trans.

Not sure with the new 6spd trans as it has a lower 1st and another OD. Something tells me they still only offer the 4.10 with no other option.

The 4.10's help with mileage not hurt it. The LS doesn't have the <1500rpm power necessary to run 3.73's at "normal" highway speeds.

h2oskier
10-16-2010, 09:23 AM
3.73 wasn't an option with 4spd trans.

Not sure with the new 6spd trans as it has a lower 1st and another OD. Something tells me they still only offer the 4.10 with no other option.

The 4.10's help with mileage not hurt it. The LS doesn't have the <1500rpm power necessary to run 3.73's at "normal" highway speeds.

Uh 2001 2500 HD with 3.73 was available i have one gets the average 10-12

White Gardens
10-16-2010, 09:33 AM
3.73 wasn't an option with 4spd trans.

Not sure with the new 6spd trans as it has a lower 1st and another OD. Something tells me they still only offer the 4.10 with no other option.

The 4.10's help with mileage not hurt it. The LS doesn't have the <1500rpm power necessary to run 3.73's at "normal" highway speeds.


4.10 hurts mileage, it doesn't help. 4.10 gives you a bit more pulling torque.

If you want MPG's go down to a 3.05 or so.

TLS
10-16-2010, 09:35 AM
Uh 2001 2500 HD with 3.73 was available i have one gets the average 10-12

With the 6.0???

And it's a 2500HD (9200GVWR)???

Pretty sure 3.73's were only available on the Duramax and 8.1's.

TLS
10-16-2010, 09:47 AM
4.10 hurts mileage, it doesn't help. 4.10 gives you a bit more pulling torque.

If you want MPG's go down to a 3.05 or so.

Wrong.

Sorry.

But the LS engine needs to keep the revs up.

With my 4.10's, at highway speed (60mph) I'm right at 2000 rpm. Any lower, and it will be downshifting out of OD EMPTY at the slightest hill.

3.05's (???) would put it UNDER 1500 rpm's and it would never hold OD until your doing 80 mph and thats IF wind drag doesn't creep in and prevent you from getting into OD.

If it were an 8.1 or a Duramax...or even an older 350, then YES the higher the rear gears, the worse the mileage. The Duramax and 8.1 are happy all day lugging around at 1500rpms.

h2oskier
10-16-2010, 09:51 AM
With the 6.0???

And it's a 2500HD (9200GVWR)???

Pretty sure 3.73's were only available on the Duramax and 8.1's.

Well i bought it new in 2001 and still drive it every day. As a matter fact i still have the window sticker 3.73 with the 4l80e tranny

TLS
10-16-2010, 09:55 AM
So you have a 2001 2500HD (9200GVWR) 6.0 4x4 with 3.73 rear gears?

White Gardens
10-16-2010, 09:59 AM
Wrong.

Sorry.

But the LS engine needs to keep the revs up.

With my 4.10's, at highway speed (60mph) I'm right at 2000 rpm. Any lower, and it will be downshifting out of OD EMPTY at the slightest hill.

3.05's (???) would put it UNDER 1500 rpm's and it would never hold OD until your doing 80 mph and thats IF wind drag doesn't creep in and prevent you from getting into OD.

If it were an 8.1 or a Duramax...or even an older 350, then YES the higher the rear gears, the worse the mileage. The Duramax and 8.1 are happy all day lugging around at 1500rpms.


Your original statement defies simple logic from a broad perspective. Now you are getting specific about specific trucks and equipment.

So am I wrong, no.

h2oskier
10-16-2010, 10:00 AM
So you have a 2001 2500HD (9200GVWR) 6.0 4x4 with 3.73 rear gears?

Mine aint 4x4 but yes drive it everyday

TLS
10-16-2010, 10:05 AM
Your original statement defies simple logic from a broad perspective. Now you are getting specific about specific trucks and equipment.

So am I wrong, no.

I don't understand your statements. :rolleyes:

We ARE specifically talking about 2500HD trucks with the 6.0 engine. They didn't offer the 3.73 option for a reason. That reason is because the 3.73's didn't have the towing capacity, and didn't get any better fuel economy.

TLS
10-16-2010, 10:07 AM
Mine aint 4x4 but yes drive it everyday

Maybe it's the 4x4 part, as I cant be without it. Perhaps the 2wd's offered the 3.73's?

But your sure you have the 6.0 and your sure you have a 2500HD (9200GVWR)?

h2oskier
10-16-2010, 10:12 AM
Well i hate to tell you guys but in less ive been dreaming since 2001 i got a regular cab 2500 HD with the 3.73 from the dealer and the window sticker to prove it. But no it is not 4x4.

TLS
10-16-2010, 11:21 AM
You got what you got!

I followed the development of the GMT800 trucks pretty closely. Even took tours of the engine assembly plants.

I do know that there were two 2500's available in M/Y 2000. One was a Classic (88-99 style)with the 5.7 or 7.4, and the other was the new body style 2500 with the 6.0 engine.
Both were 8600 GVWR
Both were available with 3.73 gears

The 2001 M/Y ushered in the 9200 GVWR and offered 6.0, 8.1, and 6.6 engines.


Just trying to clear the air.

hosejockey2002
10-16-2010, 12:30 PM
I've got an '05 2500HD, 6.0, regular cab, 2WD with a dump insert. Running around town pulling a 6x12 enclosed I get 10. Pulling my TLB drops it to about 8.5. The best I ever got was empty on the freeway, 14. I think the insert screws up the aerodynamics on the freeway and hurts MPG. Not too worried about it, though. :laugh:

Keith
10-16-2010, 01:17 PM
I think if you throw out the extremely high numbers and the extremely low numbers, almost all 3/4 and 1 ton trucks with gas engines get about the same mileage towing. No matter what brand. A 2wd might buy you another 1-1.5 mpg.

STIHL GUY
10-16-2010, 03:41 PM
i have an 05 4x4 regular cab...i get 10-12 MPG

scagrider22
10-16-2010, 07:54 PM
You got what you got!

I followed the development of the GMT800 trucks pretty closely. Even took tours of the engine assembly plants.

I do know that there were two 2500's available in M/Y 2000. One was a Classic (88-99 style)with the 5.7 or 7.4, and the other was the new body style 2500 with the 6.0 engine.
Both were 8600 GVWR
Both were available with 3.73 gears

The 2001 M/Y ushered in the 9200 GVWR and offered 6.0, 8.1, and 6.6 engines.


Just trying to clear the air.

The classic 2500 and the silverado 2500 where both available in 1999 and 2000 they were both available with 3.73 and 4.10 (4x4, not sure about 4x2). In 2001 when they started badging them HD's and all short beds 6.0 came with 3.73 gears and all long beds came with 4.10 gears, unless you special ordered the truck then you could get either one. Also Chevy didnt start making the HD in 2001 they have made them since the 1970's they just never badged them HD, its a marketing sceme to rival the "Superduty" name.

scagrider22
10-16-2010, 07:58 PM
With the 6.0???

And it's a 2500HD (9200GVWR)???

Pretty sure 3.73's were only available on the Duramax and 8.1's.

Wrong! Ive had 6.0 2500hd 4x4s with 3.73 and 4.10

scagrider22
10-16-2010, 08:00 PM
Wrong.

Sorry.

But the LS engine needs to keep the revs up.

With my 4.10's, at highway speed (60mph) I'm right at 2000 rpm. Any lower, and it will be downshifting out of OD EMPTY at the slightest hill.

3.05's (???) would put it UNDER 1500 rpm's and it would never hold OD until your doing 80 mph and thats IF wind drag doesn't creep in and prevent you from getting into OD.

If it were an 8.1 or a Duramax...or even an older 350, then YES the higher the rear gears, the worse the mileage. The Duramax and 8.1 are happy all day lugging around at 1500rpms.

You finally got one! Yes the 6.0 with 4.10 gears gets better gas mileage for driving around town and towing. On the highway with no load the 3.73 is better.

TLS
10-16-2010, 08:16 PM
Maybe it was a pre '04 thing then???

I'm not just making this up guys!!!! Lol

somewhere, some years, you didn't have an option. Kinda like the Duramax and 3.73's..... You didn't have a choice.

Could be the snowow prep required it. Or the locking rear. But some combo of what I wanted didn't give you the choice. To get the 3.73's you had to order the 8.1/Ally
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scagrider22
10-16-2010, 08:17 PM
Back to the original question, I have four trucks with 6.0 liters a 99, 03, 05, 08. The three older ones get anywhere from 8-11 mpg. The gmt-800 style gets 12-15. These engines are very cheap to operate, the 99 has 300,000 miles and still has the original drivetrain. Out of the four truck Ive have one bad starter and one bad tranny (my fault). They all tow and plow snow. I also have a couple of Ford V-10s with no problems, the only trucks I have trouble with are the diesels that everyone raves about! I wish I didnt need them I hate diesels, they are maintenance nightmares!

scagrider22
10-16-2010, 08:19 PM
Maybe it was a pre '04 thing then???

I'm not just making this up guys!!!! Lol

somewhere, some years, you didn't have an option. Kinda like the Duramax and 3.73's..... You didn't have a choice.

Could be the snowow prep required it. Or the locking rear. But some combo of what I wanted didn't give you the choice. To get the 3.73's you had to order the 8.1/Ally
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You didnt have the option with the Duramax but the 6.0 i do know from 99-07 (old style) it was an option. I bought all my trucks new and it was always an option until I bought the 08, so stop guessing.

TLS
10-16-2010, 08:24 PM
Had to be the snowplow prep then. At the time, 2001+ , I was configuring online several times a year and it was never an option you could "click" as if it was available, but something you chose prior prevented it.
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scagrider22
10-16-2010, 08:33 PM
Had to be the snowplow prep then. At the time, 2001+ , I was configuring online several times a year and it was never an option you could "click" as if it was available, but something you chose prior prevented it.
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The plow prep did affect the axle ratio also, but it was an option. Its very possible the online order form was incorrect. I was always asked what gears I wanted when ordering the trucks (except the 08) and the 05 i bought with 3.73 gears because it would not be towing as often because I used it for a personal truck. If you didnt special order the truck as I said before the long beds came with 4.10 and short beds came with 3.73.

deere615
10-17-2010, 10:49 PM
I usually get right about 10 whether towing the landscape trailer or just driving around

WHIPPLE5.7
10-22-2010, 11:04 AM
Boy thats not some very good numbers. I have a '97 and '98 2500 one with 350 and one with 454. They both get around 15-16 emtpy and 11-12 loaded so heavy the leaf springs on the truck and tandem axle trailer are about to snap. And yes the 350 does pull shitloads of weight quite easily. I had to do intake, exhaust, and custom tune but it has been known to pull 75 up a 7% grade pulling 14K.

Darryl G
10-22-2010, 12:39 PM
Easy solution. I have a 2003 Silverado 2500 HD with the 6.0L and 4:10. I just don't check my mileage. What you don't know can't hurt you, lol.

It's really irrelevant to me. I like the truck, it does what it has to including pulling 10k pounds. To me it's just the cost of doing business.

hosejockey2002
10-23-2010, 12:30 PM
And yes the 350 does pull shitloads of weight quite easily. I had to do intake, exhaust, and custom tune but it has been known to pull 75 up a 7% grade pulling 14K.

Intake, exhaust and custom tune, huh? Your name suggests you're running a blower, which you would need to even come close to what looks like a BS fish story. Looking at this chart (http://eogld.ecomm.gm.com/NASApp/mediumduty/printbook?printbooktype=weightcalc&doctype=truckselection&year=2004) (pages 10 and 11) and doing the math you need almost 400 hp at the rear wheels to do what you say, which means about 500 hp at the crank. Even if you had a blower on your 5.7 and it could produce those horsepower numbers I doubt the motor would hold up for long with that load.

WHIPPLE5.7
10-23-2010, 09:56 PM
Intake, exhaust and custom tune, huh? Your name suggests you're running a blower, which you would need to even come close to what looks like a BS fish story. Looking at this chart (http://eogld.ecomm.gm.com/NASApp/mediumduty/printbook?printbooktype=weightcalc&doctype=truckselection&year=2004) (pages 10 and 11) and doing the math you need almost 400 hp at the rear wheels to do what you say, which means about 500 hp at the crank. Even if you had a blower on your 5.7 and it could produce those horsepower numbers I doubt the motor would hold up for long with that load.

Had to put new heads on at 100,000. It now has 139,000 and its getting pretty rough. I worry alittle about long trips with it but she hasn't let me down. I'm considering selling the whole truck and buying a new Ford 6.2 F-250.

Drew Gemma
10-24-2010, 12:17 AM
2005 2500 hd reg cab long bed 4x4 w/insert get 10 mpg if you baby it. If we tow or haul anything we get 8 mpg.

Work trucks are for work not fuel economy.

mowerbrad
10-24-2010, 11:17 AM
With my 2007 Chevy 2500HD NBS, ext cab, 4x4, LS package and with 3.73 gears I can get over 20mpg at certain speeds.

Here's some figures for you...

City driving: 12-13mpg
Highway @70mph: 17mpg
Highway @55mph: 20-21mpg
Towing (without tow/haul mode on):10mpg
Towing (with tow/haul mode on): 9mpg

A typical tank with a combination of highway (40%), city(40%) and towing(20%) will average 12 mpg.

Without towing, a tank with a combination of highway (60%) and city (40%) will average 14-15mpg.

And yes I have hand calculated these numbers. Hand calculated came out as the same as what the computer read.

TLS
10-24-2010, 11:35 AM
I'm pretty sure the NBS 6.0's have VVT. Allowing cam timing to be changed depending on multiple inputs. This would allow for more torque and the ability to hold 6th gear (double overdrive) with 3.73 axle ratio. I know my standard cammed 6.0 would never be able to do so.
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