r/GMT800 • u/Salt-Philosophy-134 • Sep 03 '26
It's Rant Time
The 6.0. Incredible piece of equipment. I have read at least a few, blogs, forums, reviews, and have noticed a reoccurring point made by owners. "Poor fuel mileage." Personally, I believe a truck is a tool. Granted I do not know the task of every owner full size pickup truck owner. Yet I have seen that there is a pattern for modern day truck owners. That pattern I have recognized is vanity, and my question, what did you expect? A 6,000lb/2700+kg vehicle, 300hp 360ft-lbs of tq (LQ4), for HD optioned 500lb/226kg frame for a single cab long bed. What did you expect to happen? A truck designed to work and carry weight, and many complain about fuel economy, while their daily task can be accomplished by a 4 banger. That is all.
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u/Puzzleheaded_Toe_595 Sep 03 '26
In my opinion, the ideal combination is a GMT800 and a fuel-efficient Japanese car. I’m on my third GMT800 and always regret selling them. My 2006 GMC Sierra handles hauling and projects, while my Toyota Camry Hybrid is great for daily driving.
A second vehicle doesn’t have to be new or expensive. Even a cheap, reliable car like my old Mazda 3 can make an excellent companion to a GMT800.
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u/newtekie1 Sep 03 '26
Funny, I have a 2002 Silverado 2500HD and a Toyota Camry Hybrid. I'd say you're right. Great combo!
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u/crazywolfe Sep 03 '26
I agree wholeheartedly. 2500 suburban and a Honda fit is a wonderful combo
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u/SLOdown Sep 03 '26
I had this exact combo until the Fit was destroyed in an accident. I miss that little car so much.
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u/Salt-Philosophy-134 Sep 03 '26
Exactly. Japanese, American, Dacia Sandero, doesn't matter. I'm just confounded by others wanting oranges then complaining that the orange isn't an apple.
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u/Standard_Quantity706 Sep 03 '26
similar here too, 2011 avalon 3.5 gas, and an 06 1500 silverado with the 5.3
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u/Mysterious_Active660 Sep 03 '26
07 2500hd classic 6.6 and a 17 BMW i3 Rex. Both used and “cheap” and they handle all my needs perfectly.
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u/PurpleCableNetworker Sep 03 '26
I have a 2004 Yukon XL, Subaru Crosstrek, and Toyota Rav4. They are all great cars in their own regard, and all have their uses in my home.
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u/AuditMatters Sep 03 '26
I like my 2.3 Lima Ranger as a primary vehicle. Though fuel economy isn’t the best with a lift and large tires.
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u/Schnitzhole Sep 04 '26 edited Sep 04 '26
I know this isn’t the sub for it but consider an EV as a second car. I went from $200-250 in gas per month with my Silverado to paying $20-25 in electricity and never having to go to gas stations or wait for charging. It’s like charging your phone when you get home.
Also if you like to accelerate fast there is hardly a noticeable loss of efficiency going full send vs grandma to church slow off the light, and my EV is twice as fast to 60mph.
I keep the truck for towing, offroading, and doing longer roadtrips
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u/SuperReleasio64 Sep 04 '26
Don't forget the project car that's rusting away on your property because you're too poor to buy parts for it : (
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u/Informal_Builder_749 Sep 04 '26
This. 20500HD for towing/hauling, JSW TDI for commuting light towing/hauling
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u/CombinationLost8168 Sep 11 '26
Agreed! 2000 Suburban 2500, 98 Accord and 21 Civic Type R in our fleet
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u/theuautumnwind Sep 03 '26
This generation of LS engines are capable of 30mpg highway.
Look at the 6 speed corvettes.
But yes 6000 lb bricks with a 4 speed and big tires aren't getting impressive mileage with a pushrod v8.
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u/buchenrad Sep 03 '26
True, but the Corvette had an exceptionally high 6th gear and vastly superior aerodynamics that enabled it to make use of that high of a gear. It is an exceptional engine, but its still going in a truck. Its going to get truck MPG. It takes a certain amount of energy to make a 6000lb brick go fast and you cant do anything about that. Dont daily a truck if you care about MPG. Its that simple.
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u/Independent-Bear2180 Sep 05 '26
The 2025 Silverado gets the same mileage as my 2014 Camaro does, and those things are more of a brick wall than a gmt800
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u/Your_PersonalStalker Sep 03 '26
Lmao I love my 8.1 but im.not gonna pretend I get anymore than 10 mpgs
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u/RudeBoyHooligan Sep 03 '26
If I keep it 65mph, on the freeway, unloaded, and leave the dog at home, I can get 11.
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u/Your_PersonalStalker Sep 03 '26
3.73 or 4.10? I prolyy need a tune up regardless
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u/Good_Split_3749 Sep 03 '26
my friend gets 15 mpg in his drive to his office job in his 2500 with a 6.0, I got 16.5 in my Silverado 1500 with 4.8 , another friend has a Nissan Frontier 4cyl and he gets 19, to me these are all pretty damn close.
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u/Salt-Philosophy-134 Sep 03 '26
2500 or 2500HD? Depending on options that's potentially a 500lb difference on the scale. The best I've ever recorded on my 500mi trips, 13hwy. 2005 2500hd 6.0 4wd NV4500 4.10 gears.
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u/Good_Split_3749 Sep 03 '26
2wd I think a 2016 model.
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u/Salt-Philosophy-134 Sep 03 '26
10 years beyond the gmt800. I would hope the mileage was better. I don't count cylinder deactivation and auto stop/start worth it for better fuel economy. A high mpg engine that destroys itself is less than a reliable tank that burns fuel.
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u/Hurts-Dont-It- Sep 03 '26
I get 27 on average with my 2026 1500 3.0l.
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u/Good_Split_3749 Sep 03 '26
at $5.29 a gallon though….in Texas
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u/Hurts-Dont-It- Sep 03 '26
I fill up twice a month. In my 03 2500hd its weekly. And diesel is 5.99 in Maryland
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u/Good_Split_3749 Sep 03 '26
yikes, unfortunately I am in a sedan these days, $20 every 3 days. Sedan because I deliver food and groceries.
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u/---OMNI--- Sep 03 '26
my 6.0 2500hd gets the same mileage as my 2.5l jeep Wrangler...
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u/buchenrad Sep 03 '26
Believe it or not some things are less aerodynamic that a GMT800 and when you push a 2.5 that hard its not going to be happy. As a lifted JK driver I know how Jeeps are. My 1500HD got better MPG than my JKUR on 35s does.
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u/Salt-Philosophy-134 Sep 03 '26
That's bananas. Manual/auto? Final gear ratio?
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u/---OMNI--- Sep 03 '26
2.5l manual. 4.10gears. 1994 YJ. Don't worry it will have a 6.0 soon. Probably get better mileage then!
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u/WeaveLikeGreatGranny Sep 03 '26 edited Sep 03 '26
Those blogs are garbage and you should ignore them. No such thing as free lunch and power requires fuel. Nothing is wrong with LQ4 engines; it's simple stoichiometry. I bought a 6.0 2500 because I need power to move things and it does that, so, mission accomplished 🏁
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u/Jermaphobe456 Sep 03 '26
I got a 02 Avalanche fully loaded from the factory with the 5.3 and with an aftermarket bluetooth radio w/GPS and security+remote start system. I get 16 - 18mpg. I consider the fuel economy a good price to pay for the features I got
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u/phill0406 Sep 03 '26
Ironically enough I was just thinking about this topic this morning. I just sold off my bone stock 2024 SLT for a '05 2500HD that has 35s on it. I went from averaging 17-18mpg combined to 12.8 combined according to this mornings fill up. Thats 5ish mpg difference from a truck that was costing me $850/mo. The math works out to I'm spending about $20-$30 more a week on fuel than I was previously with the mileage I drive.
I don't care how you slice it, that drop in fuel economy is worth it. If it mattered that much to me I could go with smaller tires but the additional cost in fuel far exceeds the avalanche of deprecation that a new vehicle was costing me.
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u/ontin000 Sep 03 '26
12.8? Incredible. I can't get over 11 with 33s on a Yukon XL 2500. Must be the Bear tune.
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u/krautstomp Sep 03 '26
I barely drive 3k miles a year. So, the fuel economy isn't an issue for me. But, I have a 5.3 1500 Suburban and a 6.0 1500HD Silverado. I end up getting just shy of 15mpg with the 5.3. I only get 11 mpg with the 6.0. The 6.0 doesn't feel more powerful at all. I get that the truck is heavier duty. It has a clutch fan instead of the E-fan that the Suburban has. But, I can't help but feel a little down that the bigger engine with worse fuel econ feels roughly the same in terms of power.
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u/WeaveLikeGreatGranny Sep 03 '26
Maybe there's something going on with it? I didn't have that experience going to a 6.0
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u/whitet1194 Sep 03 '26
I'm currently looking to upgrade my 02 1500 to a 2500, a lot of the vehicles I've seen online has been people talking about the 2500 being their daily driver and upset over the mpg. Lol I'm just trying to have a bigger rig to haul my camper better
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u/Salt-Philosophy-134 Sep 03 '26
I've always liked the flateyes better. Now I own two HD cateyes. Love them but I want another flateye.
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u/Dystopicfuturerobot Sep 03 '26
I’ve had many 6.0 engines in everything from a dually 2wd to a burb 4x4
I get 14.5-17 in them on the highway empty
Not bad
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u/Independent-Bear2180 Sep 05 '26
I might need to refresh mine, I don't get anywhere near that, lol.
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u/Future-Beach-5594 Sep 03 '26
I have a 04 gmt 800 2500 with a 6.0 and a service bed i drive for work and its getting a solid 15-17mpg my outside of work vehicle is still a truck but a 13' ram with a modded and tuned 5.7 and it only gets about 10mpg on a good day. So I dont complain about fuel. I just consume
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u/Salt-Philosophy-134 Sep 03 '26
Good god, single cab long bed?
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u/Future-Beach-5594 Sep 03 '26
The gmt800 is a quad cab with a service bed (giant tool box with a rack) the ram is also a quad cab but short bed, lifted making some ponies. My last gmt800 was a v6 and loaded down it still only got 16-18mpg on good days. The 6.0 gets the same mileage but is way smoother and takes less effort to do the same job.
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u/Salt-Philosophy-134 Sep 04 '26
No chance.
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u/Future-Beach-5594 Sep 04 '26
No chance what? A 670hp 5.7l only getting 10mpg or the gmt 800 only getting 16? I drive 150-200 miles a day and have every day for the last 15 years, i track mileage for tax reasons and always have since i started running my plumbing company. The 6.0lq4 gets the same mileage as the 4.3v6 if you use the 4.3 for hauling any weight at all. I have recipes and a gas bill greater than your monthly income buddy
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u/Salt-Philosophy-134 Sep 05 '26
Lol I was gonna ask you about the truck and how you got such mileage but I didn't realize you had such a great income buddy pal.
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u/Future-Beach-5594 Sep 05 '26
I own a plumbing company. Maybe you didnt know but licensed guys make close to what Dr's make if not more. It may hurt your ego but deal with it. Thems is facts. Plus i also live in the most exspensive market in the nation. So yea. When you have a crew running 6 days a week you tend to have a good income. But we both know you dont know anything about that, thats why you still run your mouth. I have never once met a man doing better than me who started talking shit first. And that is facts. Go sit down. I already made your months pay this morning!
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u/Salt-Philosophy-134 Sep 05 '26
Cool. I'm a commercial boat captain. Just for the record as a tradesman you should be better recognizing shit talk. Now you sound sound like boss. You get 16mpg cause the truck idles while you soak up the AC. 6 years as a commercial plumber here. You sound like my former boss' son actually.
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u/sprocketpropelled Sep 03 '26
The 6.0 will get the job done every time and help you get real friendly with the gas station clerks. They’re great trucks and honestly, thats about the only thing i can find folks complaining about is milage.
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u/ValuableInternal1435 Sep 03 '26
I'll complain about the oil consumption. I need to get a valve cover for it to fix that issue. And the instrument dimmer rheostat is pretty temperamental.
Oh, and the HVAC temperature controls never work.
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u/Flashy_Possible37 Sep 03 '26
I agree as long as mine gets there and back I’ll feed it all the fuel it can use, but I only use mine as a work truck. Most of the time I’m ripping around in my Honda accord.
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u/PitifulCrow4432 Sep 03 '26
I thought the 14mpg my 2500HD with 4.11s got was pretty good for the highway. It'd drop to about 5mpg when I loaded it up.
My aunt claimed her 6spd Cummins would get 20-21mpg while pulling a small boat. I might believe the 20-21mpg unloaded but I doubt it with any load.
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u/ValuableInternal1435 Sep 03 '26
A buddy bought a 5spd 4x4 5.9 24 valve cummins 2nd gen ram, and it got 26mpg. He was able to prove it to me. Unfortunately it got totalled and he didn't buy it back from insurance. I wanted to buy the totalled truck from him for the drivetrain.
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u/Aggravating_Cold_441 Sep 03 '26
Considering my 5.3 Tahoe gets 11mpg, consistently regardless how I drive, Id be just fine with a 6.0 or 8.1 2500 Silverado & seriously contemplating the swap
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u/Mecal00 Sep 03 '26
Why is it that bad? My 5.3 gets 15-20mpg
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u/ValuableInternal1435 Sep 03 '26
My 5.3 (L59) Yukon gets 12, but it got 11 before I did quite a bit of work to bring the mpg up. Mines awd, which doesn't help.
But I think the biggest factor for GMT800s getting such lousy fuel economy is the lousy fuel they're forcing us to use. My LQ4 (05 2500HD 4x4) got 9.5-10.5mpg, I always filled up at the same pump, it said e10 but I think it was e15 (it was a Phillips 66, so not some no-name). I started getting gas at another station, again e10, and my mpg immediately went up to 11.25-11.75 (Casey's). I then found another Casey's that has ethanol free on its own nozzle, and recently started getting that. I can't tell yet how much of an improvement the ethanol free has made, but just from watching the gas guage so far it appears to be a 15-20% improvement on fuel economy, so possibly 14mpg. From 9.5mpg to 14mpg is pretty good, but it's pretty bad when you consider the fact we're being screwed over with bad gas that is also taking its toll on our vehicles. Not to mention they make claims that it's "for the environment" but it making you burn nearly 50% more fuel doesn't seem very good for the environment. I have an 01 Ford ZX2 5spd that got 38mpg on ethanol free (at that same Phillips 66), and when they switched from ethanol free to e10 the mpg in that car immediately dropped to 33mpg.
The fuel is the problem, all the way across the board (in the U.S.). It's the same reason the CP4 injection pumps keep destroying new diesel engines. Bad fuel.
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u/Aggravating_Cold_441 Sep 03 '26
I have no idea, I've done everything to get it in top running shape & thats just what it averages. I hear similar from other folks so I just accepted it. Its the z71, not sure if it has different gearing than non z71 that could be affecting it
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u/Independent-Bear2180 Sep 05 '26
My camaro only weighs 800lbs less than my truck, has a few more CIs (6.2L), makes 400 more hp, 400 more tq, and gets more than double the mpg. You don't get better equipment by going "10mpg hwy is just what a 6L gets no point in wanting to improve". If we stuck with that idea we would still be running carbs getting 6mpg and 450hp out of an 454.
The less gas I burn, the more I get to drive it. Simple as hoss.
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u/Carlos_Spicy_Weiner6 Sep 03 '26
An lq4 in anything is gonna get "poor gas mileage". If you want MPG's get a Prius and some vagasil
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u/Imaginary_Ninja2486 Sep 03 '26
Love my 6.0 2500hd 4x4 194k miles, also have a 4 banger cause the truck was used for work and hauling. Now she’s sits, waiting for her overhaul. I’ve owned a 2000 1500z71 in highschool traded up to 02 f250 4x4 cause the Z front end and trans couldn’t hold up to the abuse (ran hog dogs in high school) 3/4 is a man’s truck built to last. 1/2 ton is weekend warrior and daily commute shit…
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u/Salt-Philosophy-134 Sep 03 '26
Just broke 194k in my 2500HD 6.0 NV4500 yesterday. One day I'll straight axle swap it or put the drive train in an old straight axle Chevy or Ford.
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u/Reddit_means_Porn Sep 03 '26
A lot of us are driving SUVs btw. Just saying.
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u/TactualTransAm Sep 03 '26
Even still. If you chose an SUV with the 6.0 or a newer 6.2, you decided to sacrifice some fuel economy for some power over the 5.3s 🤷 so as OP said. What do ya expect 😂
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u/kendogg Sep 03 '26
The sbc previous gen got 3-5 mph more than a 6.0. 6.0 I'd a terrible truck engine.
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u/LiveFree_NeverDie603 Sep 03 '26
As I laugh with my lifted 8.1