Is 10 Mpg All The 6.0l Will Get?

TroyisBig · February 17, 2009

I bought a 2004 GMC 2500HD 6.0L Automatic 4:10 gear ratio for hauling hay. Around the farm its getting 8 mpg. On the road its getting 10 mpg.

Please someone tell me something is wrong with it.

It did throw an engine code. Cylinder misfire and some emission vent code.

The truck has 112k. It seems doggy to me too, for a bigger V8.

I put a set of new plugs in it and reset the codes, but it didn't help.

What is everyone else getting with this engine?

Draenor · February 17, 2009

What are the exact codes?

Have you been performing all the proper maintenance on it?

Is the MPG actual or on the DIC and is this loaded or unloaded?

mattjulien · February 17, 2009

I bought a 2004 GMC 2500HD 6.0L Automatic 4:10 gear ratio for hauling hay. Around the farm its getting 8 mpg. On the road its getting 10 mpg.

Please someone tell me something is wrong with it.

It did throw an engine code. Cylinder misfire and some emission vent code.

The truck has 112k. It seems doggy to me too, for a bigger V8.

I put a set of new plugs in it and reset the codes, but it didn't help.

What is everyone else getting with this engine?

i'd say its normal for running a 4:10. i would change the cap and rotor and that might help.

Draenor · February 17, 2009

I bought a 2004 GMC 2500HD 6.0L Automatic 4:10 gear ratio for hauling hay. Around the farm its getting 8 mpg. On the road its getting 10 mpg.

Please someone tell me something is wrong with it.

It did throw an engine code. Cylinder misfire and some emission vent code.

The truck has 112k. It seems doggy to me too, for a bigger V8.

I put a set of new plugs in it and reset the codes, but it didn't help.

What is everyone else getting with this engine?

i'd say its normal for running a 4:10. i would change the cap and rotor and that might help.

Loaded, yes....Unloaded not really. He should be able to get another 2mpg out of it.

No cap, no rotor. Coil on plug design.

mackey62 · February 17, 2009

I bought a 2004 GMC 2500HD 6.0L Automatic 4:10 gear ratio for hauling hay. Around the farm its getting 8 mpg. On the road its getting 10 mpg.

Please someone tell me something is wrong with it.

It did throw an engine code. Cylinder misfire and some emission vent code.

The truck has 112k. It seems doggy to me too, for a bigger V8.

I put a set of new plugs in it and reset the codes, but it didn't help.

What is everyone else getting with this engine?

Your not doing that bad, especially if your towing or moving heavy loads around. Just traded (today) my '04 GMC2500HD SLE Ext Cab 6.0. Never ever from day one got better than 13, hated this truck since first fill up because I got rid of a '02 Duramax stick getting 18 mpg. Unbelievable to me, got as bad as 7 mpg when plowing a few residential driveways mixed in with some highway driving. Towing my camper I figure I averaged about 10mpg. Honestly, if I had to blame one thing its the 4.10 gears. GM messed up bad when they made this the only axle ratio option, think '03 or '04 was the year they offered only 4.10 in a 6.0 2500HD. Only advice I can give is make sure you got the codes cleared up, any sensors, O2, MAP, MAF etc.. anyone can mess you up and run rich.

Not sure what your doing with it around the farm, but i imagine mine wouldn't be any better than 8mpg. 10 on the highway might be a little on the low side, depends what you call highway driving. My 20 mile commute to work, 90% 62mph, 10% 30mph, gets me about 11 mpg.

Sorry to tell you, upgrade yourself to a Dmax, '06 or older so you dont have to mess around with all the emissions crap

6pointO · February 17, 2009

Sorry to tell you, but that sounds about right man. Im getting 8MPG around town...and 12MPG if I'm lucky on Highway. Snow Plowing, man we wont even get there...lets just say its around 5.

Kinda scary, and really disappointing too.

lazer · February 17, 2009

I have a 2008 HD 6.0. It has 7,000 miles on it. My DIC says I'm getting 9.3 pulling a landscape trailer during the summer and now during the winter I'm getting 10.2 just driving short trips. And I have the 3;73 rear end. Not very happy about this.

mackey62 · February 17, 2009

Something I should have added, dont mean to badmouth the General here. When I bought the truck I knew it was a 6.0, knew it had 4.10's, knew it wasn't built to get 20 mpg. So, I'm not blamin', I'm just sayin'..........

TroyisBig · February 17, 2009

To Mackey62: Did you think the 6.0L was good on power? I've ran diesels all my life around the farm, but when diesel got to be so much higher than gas, coupled with the higher cost of service changes and maintenance I decided to try a gas burner.

Not very happy with that decision. Seems low on power. I could have the 8.1L I think and have power to spare and get better mileage. At least it wouldn't be any worse.

Thanks to everyone that replied. To answer some questions. I haven't had this truck very long. I put a flatbed on it with an electric/hydraulic bale spike on it. It's not a real heavy built bed, but would weigh quite a bit more than the factory box. It has a ranch hand bumper on the front also.

I bought the truck hit in the front, and replaced the drivers fender and the hood along with a new grill and headlight assemblies. It wasn't hit real hard. I have pics of the prior damage, but anyway when getting 8mpg it was loaded with a 1400 lb round bale of hay 1/2 the time. This feeding cattle condition I realize is a terrible way to check mileage since I'm constantly stopped opening gates and looking at cattle. I tried to get Jessica Simpson to go with me to open gates, but she doesn't like the green smelly stuff on her boots. I told her I didn't care if she got fat.

I check the mileage by simply dividing the trip mileage by the gallons on the pump.

I will try and rectify the codes. I will go down to the shop after lunch and read them out and post the exact codes, so maybe you guys can help me decifer them. I work at a Rural Electric Coop (Bad ice storm), and so we have a reader in the shop.

terryk · February 17, 2009

Hmm, I have a 2000 2500HD with the 6.0 and 4.10 gears and average 13 up and down the mountains (sea level to 3000 ft). I get 16 cruising at 65 and I think I could hit 17 if I would be nicer.

mackey62 · February 17, 2009

I have to say yes, its enough, but just barely. Someone like you, working on a farm, towing or moving heavy stuff on a daily basis, think you startign to cross that threshold where cost-benefit of a diesel comes into play. I get what your saying about addl. cost of a diesel, upfront, fuel cost, and maintenance. An 8.1, not for me, cant' really think of a situation where 8.1 would be an advantage over diesel. Maybe if diesel fuel wasnt' readily available, super cold climate, or downright plain hatred of diesel. I'd imagine you have a plentiful supply of diesel on the farm, another pro- in my opinion to go diesel. Just my opinion, but I don't think your going to see a dramatic increase in mileage with the 8.1.

Consider yourself lucky, Jessica not liking the smell was a blessing, high maintenance girl like her, probably eats a lot and doesnt show you and return on the investment. Money you saved by not having her will more than cover the new Dmax

MarkD · February 17, 2009

All of our trucks get about 30% better mileage when we actually drive them. Day to day, we get none of the "gravy" mileage. Everything is crank, drive 1 mile, turn off, crank, drive 5 miles, sit running for 5 min, drive 2 miles, turn off, crank, drive 3 miles, etc.

mackey62 · February 17, 2009

Better find out what TerryK is doing. I couldn't get 16 if it was downhill both ways. Seeing that its a 2000, wonder if its all the same emissions crap?

04silverado1500 · February 17, 2009

Hey i Heard about this new revolutionary half ton from toyota... its the new Tundra! They say its built right, you know we all want headers on our truck right!? These trucks are built in Texas which means they're bad ass! They can handle all of your towing needs. I heard they can actually pull 4 bobcats and all your tools/gas tank in the bed! Haha no really with all the heavy towing and letting the truck run while sitting still your prob fine. My gradpa and uncle farm and they would have a hard time getting any better mileage then you out of there HDs.

Supersporter40 · February 17, 2009

My 01 was pretty good when I first bought it, got 16 or 18MPG driving it home for the three hour trip. Since then it decided to not like it's new owner and settled around 12 empty. Pulling our camper trailer is 10 if we are lucky. It is also a weak POC. It has 4:10's and it still won't hold 50 m/hr without screaming in 2nd.

Our solution was to buy a truck with the 8.1. I won't get better mileage but I won't be running it's bag off to pull our trailer anymore either.

I will get a small truck for a daily driver now. Diesel is a pain up here with the cold winters and short trips. It is also a fair bit more than gas too. WHen you crunch the numbers between upkeep between the two and the cost of fuel and mileage I wonder how much better the big D is?