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  1. #1

    Default 2500HD Engine and General Questions

    Hey there. Great site here, I am bummed I haven't been on here until now.

    I currently have a 2003 Suburban Z71 with the 5.3l, I am planning on adding a 2004.5-2005 used Silverado 2500HD Crewcab to my fleet.
    I have a few questions regarding the engine options in that year, and I am looking for some real world advice and numbers.

    I am debating between the 6.0 and the 6.6 diesel.

    I would like to know what you guys are getting as far a fuel economy in these trucks when unloaded and stock? I don't want to hear all the duramax guys telling me how their mods helped, I want some stock highway/city numbers.

    I am also new to diesel, so I am cautious of how much more general maintenance and repair costs will be for the diesel over the gasoline engines. What are some typical numbers for routine maintenance of these two engines? What kind of milage can I get from these before more major maintenance is needed? When do I need to replace injectors in the duramax?

    What are the know problems with the 6.0 and 6.6? I am only looking at the LLY diesel.

    For these trucks, what would you consider a good milage to buy. I am looking to spend around $19,000. I understand the diesel will be higher then the gas, but what would be a good milage for that price point considering I am getting a well loaded truck. (LT)

    Thanks for all the help. I look forward to using the site.

  2. #2
    TRPLXL2's Avatar
    Join Date
    Jan 2009
    Norwalk, Ohio
    Blog Entries


    I have an 05' silverado 2500HD that I absolutely love, 6.0 with automatic 2 wheel drive completely stock. I get 14mpg no matter what, I know there are some guys on here that say they get 19mpg with this truck and there full of it. Unless you drive 45mph on the highway you'll never get it, that motor is meant to run!! I have never had a diesel though, hopefully one of the guys will chime in.

  3. #3


    Thanks for the information. Do you have a 6 speed trans or some thing? I have the 5.3l and I am getting very close to that. I don't know how much of a difference 4x4 will make over 4x2 though. I am wondering what the Duramax guys will say.

  4. #4


    I have the 6.0 in a 4 wheel drive and average about 12 mpg can occasionaly get 13 if I drive 55-60 (before and after lift). engines been good, but diesel should get you better mileage.
    2004 Silverado 2500 Crew Cab 4x4, AMSOIL EA air filter, Granatelli MAF sensor, Throttle body spacer, Magnaflow exhaust (true dual to 2 in 1 out muffler), 6" ProComp lift (add a leaf and 5" superlift rear block), Bilstein shocks, 35's (Cooper Disoverer ST) and 4.10 gears, Rhino Liner, EGRUSA fender Flares and widow visors, extended stainless steel brake lines, firestone airbags w/onboard air compressor, Pioneer Avic X940BT navigation, Accel backup camera.
    1960 Land Rover Series II 88
    2001 Pontiac Sunfire
    2013 Toyota Avalon Limited (Wife's Car)
    NRA Life Member

  5. #5


    '03 2500HD 6.0L, I love the engine. Gas mileage is around the 12mpg mark if I don't get on it. More than enough power stock and it handles mods really well. I am in PA and I bought my truck a little over three years ago from a local dealership; paid $11,995, had under 65k miles and in really good condition. Personally, I wouldn't pay over $10,000 for a vehicle with 100k+ miles but I have seen places asking that kind of money.
    2003 Silverado 2500HD 6.0L Vortec V8
    2" Body Lift
    3" Suspension Lift
    Skyjacker Hydro 7000 Shocks
    Skyjacker Steering Stabilizer
    35" Tires with 20" American Racing Rims
    Velocity Cold Air Intake
    Billet Throttle Body Spacer
    BBK Performance Headers
    MBRP Cat-Back Exhaust System
    DiabloSport Predator- Soon to be tuned by Diablew

    "Soon to be leveling-kit"

  6. #6


    I've got the 6.0 in my 2500 and I only get about 10 to 11 mpg's on a good day and mines only a regular cab. I wish I got about 14!

    2006 Duramax LBZ
    Edge Evo
    4'' Diamond eye to 6'' tip
    16'' ion alloy, 33'' fierce attitudes
    Lots of work left to do!

  7. #7
    Sr. Mechanic ChevyHD's Avatar
    Join Date
    Jan 2011
    Elberon, Iowa, United States


    My 02 6.0 gets roughly 12 or so and even when Im towing a 10,000+ lbs load, i get about 10. I like my truck, but my next truck will be diesel. Wasn't justifiable for me to get one before college. Its a lot about opinion though. If its justifiable for you to buy a diesel because your actually going to use it for towing and work, I say go for it. The LLY is one of my favorite engines made. They came out witht the variable geometry turbo that year as well as cold start managment. I would say you could get over 15 mpg with her even towing, if you drive normal and not hot roddin' around. Usually with duramax, i hear around 100,000 miles are so, its good to get the injectors replaced because they are starting to go bad. Its not a cheap thing to do either but once its done, you shouldn't have to worry about it again for a long time. The dmax/allison combo will run forever if you take care of it. An added maintenance with diesel is changing fuel filters. Like I said, Ive never owned a duramax so im just going off what Ive learned through research so it would be best for a dmax owner to tell you prices for maintenance and the kind of mileage they get but I was bored at work and just wanted to talk diesel so hope this helps!
    2004.5 CCSB Duramax
    Max Effort Tuning by Idaho Rob - Goerend Transmission - PCV ReRoute - EGR Blocked - Plugged Resonator - 5" Diamond Eye Turbo Back - Tie Rod Sleeves - All On Mod - Edge Insight CTS - Recon Taillights, Cab Lights, & 3rd Brake Light

  8. #8


    Welcome to the club, Brennan. Diesels do get better mpg's, but they are alot harder/money to get worked on.

    2005 Chevy Silverado Z71 Crew Cab
    6" Skyjacker lift w/Edlebrock dual front remote resoviour shocks, single rear remote. Rancho skid-plate.
    17" x 9" M/T Classic Lock Wheels, 35" BFG A/T or M/T tires
    4.10 PercisionGears w/factory locker, T/A Performance rear-end cover
    Banks CAI intake, ported throttlebody, JBA coated headers, over-sized Magnaflow cats, Magnaflow cat back exhaust, Diablo tuned
    B&M aluminum deep transmission pan
    Warn brush guard w/Warn 9.5 XP winch, PIAA bulbs, Line-X bedliner, AWS Black tool chest, Extang tonneau cover
    Weather Tech floor mats
    Cover-Craft seat covers
    Dash mat cover
    Formula One window tint
    One black Lab in rear seat.

  9. #9
    Jr. Mechanic
    Join Date
    Nov 2011
    Central Illinois


    My 2004 2500HD Crew Cab LT 4x4 6.0L averages 11.5mpg city and 12.5mpg highway with no load.
    Pulling my 24' pontoon (only 4500lb but pulls like it is much heavier because it has so much drag) I get about 8.0mpg.
    I bought it in October of 2008 with 28k on it. I paid about $19.5k. With only 67k on it now it still books at $16.5k. Not too shabby!
    I had an 2004 F250 Crew Cab Lariat 4x4 with the 5.4L (largest ford gas v8 available in 04). The 2004 2500HD is a MUCH better truck! IMHO is beats the ford in every category.

  10. #10
    Master Mechanic silverhobey's Avatar
    Join Date
    Oct 2010
    Cobourg, Ontario, Canada
    Blog Entries


    wish I could add a 2500HD to my small fleet......I personally would go gas ....diesel is a little noisier in our small subdivision.
    I know people who also have gotten 'close - to - stuck' for diesel when out touring or away on holidyas....good luck to which-ever
    you decide on. Brian from Canada
    Silverado Crew.....4.8 L

    ---Pendaliner BoxLiner and Side Rails....Van and Truck World
    ---Reese Adjustable Step Down Trailer Hitch....Van and Truck World
    ---PUTCO chrome eyebrow Mirror Covers.... Van and Truck World
    ---PUTCO chrome Bowtie 3rd Brake Light Cover....Van and Truck World
    ---DeeZee TailGate Assist ....Van and Truck World ( now Action Car and Truck Accessories )

    ---Westin Series side steps....Apple Auto Glass
    ---TRIFOLD rear soft Tonneau....Apple Auto Glass

    ---Chevrolet Bowtie Mudflaps...GM Dealer
    ---GM Rear Wheel Well liners...GM Dealer
    ---GM Front Black Tow Hooks w Hloks
    ---GM Chrome Tailgate Handle/matching key-lock....GM Dealer
    ---GM Driver Information Center Upgrade...GM Dealer
    ---GM Front Tinted Bug Deflector...GM Dealer
    ---GM Chrome Door Handles....GM Dealer

    ---Better Built rear hitch step .... Lowe's !!!
    ---AVS Window VentVisors...Canadian Tire
    ---AVS tinted License plate covers....Wal-Mart

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