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How to get better fuel economy w/your diesel



  • Off road fuel has no highway taxes and they dye it pink so they can dip test your fuel tank but it does not produce a smoke I have seen it run in several trucks and it doesn't smoke at all.but be carefull if you are running it in a on road truck or even if you are driving equipment( bobcat,tractor) on the road the fine is severe.
  • rodougrodoug Posts: 5
    I'm new to diesels and am trying to determine what to replace my Chev 3/4 ton HD gas with. Would love to have car and truck but cannot afford it so this needs to be versatile. I drive to/from work ~40mi roundtrip plus haul a 8 - 11 thousand lb horsetrailer on weekends & vacations. I am wondering what the difference in mileage would be in mixed city/highway driving unloaded would be between the 4x2 and 4x4 and the 250 and 350. I am also wondering what it would be between straight highway speeds avg 70 loaded and unloaded. If anyone can share any info I would appreciate it. I can't find any official data anywhere and most of the Ford dealers have no personal experience. Thanks in advace.
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    Several more factors you need to consider...
    - cab size
    - bed size
    - terrain (flat, hills, mountains)
    - seasonal weather
    - tractional needs (winter, off-road, boat ramp)

    The best will obviously be the lightest - which would be an F250 regular cab 4x2; the worst is obviously the F350 4x4 crew cab dually. You'll need to determine what your cab needs are, what will be in the bed, and how and where you drive. Once you have a good idea what truck configuration is best suited, others can give you an idea of the mileage. Be sure to browse the Ford F-Series Real World MPG Numbers discussion as well.

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  • rodougrodoug Posts: 5
    I have to have a crew cab due to 2-3 little ones in the back. I am pulling a gooseneck trailer and can use a long or short bed. Most of the time the bed will be empty. I'd love to have a duelly, but it's too big for all the in-town driving I do. The greatest percentage of mileage is a mix of city/highway mostly in the flat areas. I would rather have the 4x2 but I have heard the diesel is a heavy engine and you need a 4x4 if you will be in any soft dirt or mud. It doesn't snow much in Dallas so snowy weather isn't an issue. It does get pretty hot here in the summer, but I don't know if hot weather makes a difference. The Ford dealers I have spoken with have said that I could expect 2-4 mpg better from the 4x2 over the 4x4. Does that sound reasonable. I'll check out the other discussion as well. Thanks!
  • Hi, I have the 2008 f-250 crew cab diesel 4x4 short bed 373 gears lariat. I,m pushing 16000 miles on the truck. At 70 mph I get around 16.5 mpg solo. At 60 mph I get around 18mpg solo. I filled up today and got 14 mpg mixed . This is a 10 mile commute to work letting truck warm up 5 to 10 minutes in morning to defrost windows. city only I get 12.5 to 13 mpg. Pulling 9000 lb trailer with wife 3 teenagers, the bed loaded down with 5 bicycles lawn chairs fishing gear , grills camping stoves the works I got 9.0 to 9.3 mpg. this was at 65 to 70 mph and with only 3000 miles on truck. Pulling power is awesome set cruise on 70 and forget load is there. Highly recommend tail gate step and tow mirror option. Step saves a lot of wear and tear on back and folding mirrors makes driving thru bank atms and mcdonalds drive thru a whole lot easier
  • Thanks for the info. I really appreciate real world numbers.
  • Are you really having that good of fuel mileage with our 6.4L Diesel. I have the 08 XLT 6.4L Crew Cab, 20" aluminum wheels with almost 4000miles to date and I drive about 60% highway / 40% city and I just filled up today, 2-21-08, and my average was 11.8 mpg and thats at approx.70mph on the high tops. Now my 2005 6.0L Diesel was getting your kind of mileage but not my new 2008.

    I would be interested in conversing with you about your 08. my email address is

  • Hi John, If your truck does like mine your mileage should continue to improve for several thousand more miles. These engines are built with tight ring tolerances and take a while to break in. Also my driving is probably 75% rural 25% city and I drive consertive to get more mileage. I have also found that speed realy affects mileage. The other day on a long stretch of rural road I decided to experiment with mileage and speed. Using the mileage computer I dropped down to around 50 mph for about 5 to six miles and was showing around 24 mpg, 55 gave me 22 mpg, 60 gave me 20.5 and 65 was 19.3. Now I have never gotten as good of mileage as the computer shows when I calculate miles by gallons but I figured this would give me some ideal how much speed would effect mileage. Also I noticed that steep hills really effective mileage also. These are very heavy trucks. Mine weighs 7980 lbs empty with a full tank of fuel, so the amount of start and stops and hills will really affect individual mileage results. The price of diesel is hurting all of us but I,m still enjoying my truck. A couple of other things to watch is air pressure in tires I keep mine at 65 psig this is 18 inch rims and keep a check on the fuel water seperater. I do think you will see a 2 to 3 mpg improvement as you get more miles on your truck. Hope this info helps a little , will email you later. Thanks Frank
  • does your '08 warm up in the 5 to 10 minutes that you let it warm up. I am in the St. Louis area and my truck will not warm up when I first start it at home with my auto start. I have to be 10 miles down the road before it start blowing warm air. When it gets really cold I have to take it out on the highway to get it to warm up. Not to sure if this is normal for other 08 diesels or not. My '05 diesel that I traded in warmed up much quicker.

    Any info about your warm up time would be thankful
  • jim314jim314 Posts: 491
    I thought that not warming up at idle was a feature of almost all diesel engines. The diesel cycle allows such a lean burn that at minimum idle the engine simply does not make enough waste heat to keep the engine warm.

    I believe that some diesel engines can actually experience excess engine wear to the point of damage, if run at idle for an extended period--maybe an hour or two. The Mercedes inline-5 cyl diesel engine used in the Sprinter van actually had an option called "high idle", which I presume would be used to keep the interior warm if it had to be idled for an extended period say with a sighseeing application, or caught in a traffic snarl.

    So I don't think you should use a remote start to try to warm-up your diesel by idling it for 10 minutes. Start it up and drive away immediately. It would however, benefit from a block heater on a timer.
  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    Totally correct. This is why tractor trailers cover their grilles in winter - it's the only way the radiator will maintain heat.

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  • John,Here in Rock Hill SC it does not get as cold as St Louis. 18 to mid 20s for lows is about as bad as it gets except maybe a week in January were we might see a couple of nights near 10 degrees. But letting the truck warm for about 5 to 10 minutes will clear the frost and ice off the windows . The air from the vents is warm but not hot and the temp gage will be in the lowest part of the normal range. It takes about a mile of driving for it to get fully warmed up to normal temp.
  • jim314jim314 Posts: 491
    "Cummins Engine Co. states that it is three times harder on an engine when idling than pulling a load down the highway. It is much more economical to purchase a generator or a diesel-fired cab and engine heater than to idle your engine. Diesel engines are not built to be used as heaters."

    The preceeding quote was in reference to large truck diesels, but Mercedes did offer an axiliary diesel fuel heater in their Sprinter van. Of course, it may in fact not be worth it to go to the trouble and expense of buying and installing a generator or diesel-fired cab and engine heater for the few days you might really need it. I am not familiar with these auxiliary heaters, their cost and maintenance issues.
  • Thanks alot for the info. May I ask again what year your your super duty diesel is? Also if you dont mind may I print your reply and use it in my arbitration case. I need to show Ford that my '08 is not functioning properly comparing to other '08's. Ford has since come back to me since starting the arbitration saying that my 5 check engine lights for low engine operating temperature warming problem is NOT a problem and my truck is run correctly. I do know that my 2005 6.0 diesel would warm up just as you explained your is warming up, and my '08 is just the opposite.

    John W.
  • Hi John, My truck is a 2008 with the 6.4 diesel. Yesterday I took it to the dealer for a oil and fuel filter change. I spoke to the mechanic about letting the truck warm on cold mornings . His opinion was that its not a bad idea to let one warm up for a few minutes before driving off. He is one of two mechanics certified to work on the new 6.4 at this dealership. I don't mind you using my reply in your case. Do remember that the 6.4 has a total of 6 different radiators to keep things cool. The main radiator is about 20 percent larger than the one in the 06. So the 08 is naturally going to take longer to warm than the 06, but it should still warm up some. I will agree with some of the other post that a block heater in colder climates may not be a bad idea. They are not to hard to install and some will install in the radiator hose line. Several years back those were about 80 dollars, I have not priced one lately. Hope this helps Frank
  • Ford does offer an auixilary cab heater and engine block heaters on their 08 trucks.Neither option was that much, I believe the cab heater was around 200 dollars and the engine block heater was around a 100 dollars. If I had done a factory order I would have got both options. however the main option I wanted was the in dash nav system and their were only 5 trucks within 200 miles of me with the nav and the color that I wanted and none of those had the cab heater or block heater. While I agree that letting a truck idle for 30 minutes to an hour is excessive I consider a five minute warm up in cold weather to be a normal warm up time. To not let it warm up enough to clear the windows is both illeagle and unsafe. While I haven't had experience working on truck diesels I have had experience working on standby diesel generators every thing from a 5 hp pull cord up to a 16 cylinder 8 turbo 10 thousand horse power unit with a 17 inch bore and 21 inch stroke that sips fuel at about 43 gallons per minute. Each of these were set to run at idle for 3 minutes to come to operating speed and temp before engaging load and after running under load each was set to run at least 10 minutes no load to cool down before shutting down. Ford recommends at least a 3 minute cool down on the 6.4 to cool the turbos after running under load. All of these engines would be 15 to 30 years old today so I can't say what a modern cummings engine would do but the ones i used to work on would generate heat and a lot of it at idle.
  • My '07 GMC Duramax w/ 15k miles gets a dismal 13.7 mpg max. It doesn't seem to matter if I am driving in town or on the highway. If I'm towing, it goes down to 11 mpg. That doesn't concern me as much as the absolutely awful gas mileage on average. My [now probably in Mexico because it was stolen] '03 F-250 got 18 mpg in town/22 hwy, so this was a bit of a shock. I waited not-so-patiently for the engine to get a few thousand miles on it, thinking the mpg would improve, but it hasn't. With diesel prices at this hour $4.59/gal. here in the SW part of NM, I would like any input on chips that might improve gas mileage. I'm not interested in more HP or torque. Am I dreaming?
  • I have the Ford 2008 F250 Lariat Crew Cab 4X4 short bed with the 6.4 Diesel. I've owned it for about 3 months and have 7500 miles on it. The new diesel engine/exhaust is programmed by the factory to go into a "soot burn-off" mode whenever the exhaust soot collector starts loading up. On my truck, I've noticed the burn-off happens about every 300 miles. During the burn-off period (usually about 15 miles of hiway driving) the MPG will drop down to about 12mpg. After the burn off period is complete, the MPG pops right back up to its normal value. For my F250, that's about 18mpg on the hwy at 65mph.

    My Ford dealership was unable to explain the 12mpg when I asked them about it, so I had to do some investigation to figure out what was going on.

    As for the fuel mileage trend while the engine is breaking in, I've kept pretty good numbers on my mileage, and 90% of my miles are commuting between Arlington and Seattle - a 100 mile round trip at freeway speeds. When new, my truck got about 14mpg. Now, with 7500 miles, I'm getting about 18mpg. This drops to about 15mpg when I'm tooling around town. I expect that mileage will continue to improve another MPG or two as the engine breaks in...

    As a comparison, I traded in a gas 5.4 Triton 2005 F-150 that was getting about 16.5mpg doing the same type of driving. Doing the math, it costs me 27cents/mile to drive my diesel F-250. It cost me 25.5 cents/mile to drive my gas F-150.

    Am I happy with my diesel performance? Yep! Still trying to justify a chip. If I could find one that has proven increase in MPG without playing with the fuel injectors, I would be interested. I'm pretty sure that the only way to improve gas mileage is to tighten up the shift pattern. :shades:
  • jonbyrdjonbyrd Posts: 1
    Hey..people..have you ever heard of running a car on water.?

    This is true,Why should we bother thinking about how to increase the mileage of the car using diesel.Even if we can increase the mileage its is still costly for us ,As the prices of crude oil are increasing day by day.So we should think of making a few alterations to the engine.We can run the car by the electrolysis of water producing Hydroxy gas.This is what called as HHO fuel.Lets think of it once.I have also seen some useful information in the site

    I have given this idea because I have seen some of the people in the above posts saying that Its costing them a lot at a very low mileage and even the mechanics are charging a large amount of money.

    I'm expecting a great milage at low cost using the HHO fuel
    I hope you get what am saying.
  • Hello Everyone,

    I just joined this website after first researching hybrid cars etc. then fuel cell vehicles, and came across a site that said water could be used for fuel. :confuse: My husband and I have a 2006 350 Ford Super Duty outfitted "to pull a house" bought with the intention of pulling a really big fifth wheel now used to pull a horse trailer and bought when diesel was "cheaper" than gas. Our other vehicle is a 2002 little Ford T-Bird and that is not fuel efficient. Our truck gets 14.9 miles per diesel gallon even not pulling. :cry: Any thoughts on this??????????????

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