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Chevy Silverado and GMC Sierra Duramax Fuel Mileage



  • you can go on to their site and enter yr/model and if they have one it will come up. THX for the info on the Amsoil...have you seen any MPG as a result of using Amsoil?
  • Okay, I'll give it a look. Thanks for the info there. As for my currant truck I have not put it in yet. Its not boke in. As for other trucks, which were all gas, yes. Believe this or not. I have an 86 Chevy crew cab dually, 454, 4 wheel drive. I got almost 16 miles to the gallon on a trip to North Carolina with it. It wasn't my idea to take it, that was a now ex's idea. Plus my other vehicles I have put it in have increased in mileage too. I am looking forward to see how it does in my Duramax.
  • I will have to check but I suspect that you are not going to be able to run synthetic oil in a diesel. I'm open to comments
  • I'm going to do more research as well. I still plan on giving it a try. Right now I use Rotella. Everything I've heard and read its the best conventional oil on the market for a diesel. I would like to know if anyone else has any insight on synthetic oils in a duramax too. Let us know folks!
  • I just did a quick Google search and I was pleasantly surprised to see the following:
    Based on what this says...I'm willing to give it try after I ask to see if it would void any warranties.
  • You know I must of just taken a stupid pill! I just remembered that my wife's Jetta diesel gets synthetic oil every 10K miles,,,btw...we get 48-50 MPG
  • That is an interesting site. Being an Amsoil preferred customer I do get literature on their tests. The wear tests are very impressive. They also have several fuel additives for diesels too. If you look further in to Amsoil look at becoming a preferred customer also. It will save you a lot in the long run. Especially if you start using it other vehicles. I was changing oil on 8 for a while. Conventional oil was costing me on that. I switched to Amsoil and their extended service oils...I saved $700.00 in oil changes alone. Plus the fuel mileage increases, but as I said before it was on gas engines. After looking at what that site says about rotella I might use a different conventional oil too.

    "Chevrolet Duramax Diesel Owners

    Learn about AMSOIL synthetic motor oil from experienced Diesel Truck Engineers and Lubrication Specialists right here in the auto and truck engineering and manufacturing capital of the world- Detroit, Michigan.

    We are diesel engine, powertrain and chassis experts and are here to help you achieve optimum performance and longevity from your truck.

    You've spent your hard earned money on the Duramax Diesel option in one of the most popular and well engineered trucks there is, now don't you think you owe it to yourself to use the very best oil in it? And don't let your local dealership service center tell you that you you have to use their brand of oil to "maintain your warranty". That is a false statement by the dealership, yet it goes on day in and day out. We constantly receive calls from customers that were told this by their servicing dealership. This practice is not authorized or condoned by the auto manufacturers, but the fact is it still goes on.

    How a servicing dealership can essentially tell a customer that they have to use a lower quality oil than AMSOIL to "maintain their warranty" is not only wrong but it is also illegal unless they provide it free of charge. There are Federal laws that protect you against this. Please read our Warranty Laws You Need to Know section of this website to learn more or send us an email.

    Take a look at the varnish deposits in this picture below. These are the results of a severe high temperature deposit test. The one at the far right is AMSOIL Synthetic 15W-40 Diesel oil and the others are major brand petroleum diesel oils. (left to right: Chevron Delo 400, Cummins Premium Blue, Shell Rotella T, AMSOIL 15W-40). The test clearly shows that AMSOIL keeps engines cleaner longer than other major brand diesel oils do. Which oil would you rather have protecting your engine?"
  • That is even more interesting. I need to dig deeper in to their web site. I'm a customer, I should! lol I know if you plan on keeping your vehicle for any extended time their bypass filters are a wise investment also.
  • I have a 2004 model and am starting to get injector problems, so I am interested in that recall that "jbull454GMC" is refering to. They have replaced one under warranty but the truck still smells of unburnt diesel fuel. The engine surges when driven under 1500rpm too. Apparently the extended warranty company (GM) will not pay to replace all the injectors which the dealership wanted to do.

    Plenty of power, always did even with the first really bad injector. A few other niggling complaints of sticky steering when first started and turning out of a parking space and that damn rattle from the steering shaft even after they replaced it.
  • I dont know if this helps but, I had a 2002 and I got a letter from GM extending the injectors out another 100K ...a total of 200K...maybe tat was just for that truck year of 2002.
  • They have extended the warranty on the injectors. You will need to get with your dealership on that. If there is a hassle I would concider calling either Chevrolet or GMC customer assistance depending on what you have.
  • I run Amsoil 15-40 In a 2002 Duramax CCSB in Michigan and it runs great, although I do run PowerService with every tank, and plug it in when it gets down around 5 or less, just so it will start up easier and always let it warm up 10-20 minutes. Even when I havn't had it plugged in it will still start great down to atleast -15...thats the coldest I've had to start it. It's not only the oil that Amsoil has that is outstanding, but their oil filters filter small particles than others which keeps your engine cleaner from dirt or whatever else makes it's way in there. It basically makes an engine perform better for longer.
  • Thanks for the info. My GMC is almost broken in enough I can begin running Amsoil. I currantly use it in my gas vehicles and I must say, I'm very impressed. As a tip for those who have portable generators also: Running a good synthetic oil such as Amsoil will up the loaded running time 20-50% I have found. I let my Duramax warm up 10 to 20 minutes also. It has a factory remote start that lets it run 10 minutes so that makes it easy for me. I am looking forward to running Amsoil in my Duramax just to see how the milage improves too. Thanks again and take care!
  • I just bought a 08' LTZ 4X4 Duramax/Allison and I have got 19 mpg on the highway . Yes they have choked the exhaust down and it is not removable except the muffler. My 2001 had just a muffler and I never got below 20mpg's but it was manual shift. If you are interested in my truck it is 4 sale . The judge gave the X the camper so I don't need a diesel now . I have to down size. My e-mail is [email protected] and I can deliver some what .
  • losman54losman54 Posts: 22
    I got a new 2007GMC TopKick 4500 pickup body left over this last Dec. customized by Monroe Truck Equipment with all of the works. I drove it it back a 1,0000 and got 15-16 HWY MPG not hooked up to anything. I just put Amsoil new product for 2007 plus Duramax. Let's see if it improves my MPG.
  • riskyrisky Posts: 1
    I just got a 2008 gmc duramax 2500 in dec, and just towed my bike trailer with 4 bikes and got 11.3 mpg avg for the trip down and back from MN To FL . When im not pulling anything i get about 16-19 mpg. but it is still cold out and when it warms up im hoping to get a little better because when i was in Florida and not pulling anything I got about 19-20 at about 75 degrees. I have about 6000 mile on it now and i will be switching to Amsoil 5W 40 for my first oil change. I hope to get a 1 mpg better. Wait and see!
  • robhen1robhen1 Posts: 1
    I have a 2007.5 at 6000 miles I drove from texas to florida at 75mph I got 20mpg but at 16000 it dropped now at 32000 I'm down to 13.5-14.5 mpg. Is there a fix for this. at this rate of decline I'll have to park it. Chev dealer said there is nothing they can do.
  • I bought my 2500HD Duramax 4x4 in July 2004 brand new. According to the computer, it averages 15.9mpg from the day I bought it, never much varies more than a few decimal points either way. Doesn't seem to care whether I am driving in town, or at 70+mph on the freeways, towing a car hauler or empty, still does about the same economy.
    I live in rural high desert Arizona with longer trips with less traffic than many city dewellers, but with plenty of big hills. Never seen some of these amazing mpg figures that get posted on the internet.
  • losman54losman54 Posts: 22
    your right the difference in air mass is going to make a difference. I would try to get a K &N air filter (I don't any stock in the company, but I found it to make a difference). Also I would try to get a "AeroShield Wind Deflector" or a regular air deflector. Keeping it under 65 MPH will help. I just started putting Amsoil 5-40 too in my GMC topkick which has 10,000 on it...right now I'm not seeing any noticeable difference. Good Luck
  • I see we are getting some info on this. Thanks to everyone, Its all very helpful, and mostly dicouraging. The federal government has slapped us in the face once again...It was their idea for the DPF. I'm now doing trying which fuels from which company do better on milage. Walmart, which was the cheapest, got me an average of 15mpg but most of my driving has been start stop. I'm trying BP now. It seems to be doing better with mid 16's on mpg. It also seems to have a bit more power. I've also tried Miejer's standard fuel and biodiesel. Standard was same as Walmart. With Bio it got worse milage, but the milage seemed better than its normal milage after the standard diesel was in the tank again. I know that biodiesel does have better cleaning properties and they say you need to change your filter more often. I think when its time to change the filter I will run a full tank of bio through first. The down fall of my test is that I live in Ohio. We have no fuel testing laws, so we end up with the literal crap from the tanks. So I will see what happens with my research and post it all here. Plus when I switch to Amsoil I'll see what happens. Also another friend of mine runs Lucas fuel treatment. He says he sees improvement in his 04 duramax. Cost effective I don't know yet, but after I find out the best fuel to run I'm going to give it a shot. Thanks again averyone and keep the ideas coming for all of us!
  • kodiak12kodiak12 Posts: 1
    Can any one tell me if, since their correction in the 2nd half of 2004, the injector problem that the Duramax had been having has been eliminated or significantly reduced? I"m considering buying a 3500 dually and would like to know how far back I could safely go in model years without an injector problem. Any and all input would be greatly appreciated.
  • I work for a Chevy Dealer. In all of the injector replacements I've seen there have been no more problems, but...I don't think people in this area have put enough miles on them yet either. Although, the Japanese are very particular about things. Isuzu probably informed Bosch to get it right or get lost. I've found out that the Duramax was built to be a million mile engine. So in all actuallity I'd say you were safe in buying as long as the truck isn't abused or anything.
  • As far as I am aware when the LLY engine with the redesigned heads was introduced was when the main injector problem was cured. That being said, my 2004 LLY engine has had 3 injectors replaced at around 50,000 miles. They blamed it on the injector pump as I also had a rough idle and hunting at slow speeds.
    Extended warrantys are good, I extended the factory one and will extend it again next year if the option is still available especially as my truck has only just over 52,000 miles on it.
  • I have a 2003 Chevy Silverado 2500HD Duramax with cooking oil conversion that is throwing a low fuel rail pressure code. I push on the gas and it acts like it is out of gas and wont go over 1500 rpms.
  • Probably clogged up the fuel system using that gunk.
    Monitored this used cooking oil fuel with a bunch of friends who ran bus conversions and many dumped the system because it was so labor intensive. Forget to swqtch over to regular fuel before shutting off the engine for the day just once and you had a bunch of cleaning out before you were on the road unless you were really lucky. Fuel has to be heated to keep it flowing properly, etc, what a pain.
    I could see using used cooking oil if you drove all day and night but for day to day, what a pain it can be.
  • smokinsmokin Posts: 1
    I have a 2006 Duramax milage is OK 16-18 mpg. BUT when I reslly get on the pedal the exaust pours out a HUGE cloud of black smoke. I am I running too rich or is this normal??
  • roland3roland3 Posts: 431
    ... Are you heating, starting and shutting down on regular Diesel fuel like m.britt says, and also changing filters more frequently. I don't think it would be that much problem for one POV.
  • madbrit427madbrit427 Posts: 11
    Take it back to your dealer, you did buy an extended warranty didn't you? Anyway, it should be covered under the 5 year 100K engine warranty.
    I had bad smoke and a really stinky exhaust. After two trips to the dealer, they had replaced 3 injectors, the fuel pump and goodness knows what else and it seems good now (touch wood!!!). But I still don't know what the problem was as they appeared to change parts until the problem was cured. They did say the faulty fuel pump pressure had damaged the injectors.
    Great truck, just love it, but it goes away when the warranty runs out...... LOL.
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