improving fuel economy for dummies

I have a 2001 Dak 4x4, 4.7L. It used to get better mileage than it does now - I daresay it's topping off at 12 or 14 highway (possibly less, I haven't done an actual measurement), when it was getting 19/20 highway
when new.
I'm not a mechanic, and being in England, do not have access to a Dodge dealer (closest is the Jeep/Chrysler dealer). I do, however, have access to a hobby shop on base, that'll do a variety of minor repairs/services. I don't mind doing my own work, with proper instructions.
There's nothing wrong with the truck that I can tell. It gets the ol' "evaporative emission leak" error code, despite the new gas cap, but I'm told that'll not affect the truck's performance.
The poor fuel economy didn't worry me as much before, but now that the rules on base have changed, and I'll be paying $6.50 per gallon for gas on vacation, it's become more of a concern.
Anything I can do to help improve the gas mileage? Anything I should be looking at (perhaps some preventative/standard maintenance I may have overlooked) that would explain the dropping mpg?
Thanks for your help!
jmc
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The last time that happened to my older Dak, it was the O2 sensor.
What were you paying for gas when not on vacation?
--

FMB
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Suddenly, without warning, FMB exclaimed (4/29/2005 3:04 PM):

I pay about half that when I can use the station on base or gas coupons. The base station is being renovated, so it's coupons only, which can only be used to buy to/from work petrol.
jmc
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jmc wrote:

places where we could use our coupons, but they're getting fewer and farther apart! Had a Dodge Caravan that we ferried over to Ireland (from Swansea) for vacation, had to top off with "economy" petrol in Ireland before crossing back into Wales, cost $60 for 12 gallons, and that was back in the early 90's. Are you at the place with LN on the tails?
jph
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The evap code may be the key. If you have a leak, you would not expect to get very good mileage, would you? Gas thet never gets to the engine doesn't do you much good. I'd strongly suspect a perforated fuel line or a leak near the top of the tank.
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Suddenly, without warning, FMB exclaimed (4/29/2005 3:04 PM):

Ok, I'm getting back to this a little late... By the look of the part, it doesn't seem hard to replace an oxygen sensor, though it appears (according to the site I was looking at) the Dak needs two, and they're in the rear somewheres? Where do I find the 02 sensor on a 2001 Dak, and how hard is it to replace?
jmc
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follow the exhaust pipes from the manifold back and you should be able to readilly spot the O2 sensors screwed into the pipe(s) somewhere along the way usually one or more before the cat converter and one after

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The type of tire tread/design and air pressure can have a very significant effect on fuel consumption. You should have a tread that is designed for best treadwear and keep the pressure up toward the high end of limits for best results. That will affect handling, especially on wet roads, so take care.
I put a topper on my truck and gained about 1 mpg.
Keep clean air filters and clean oil.
The vacuum leak should be fixed, mine has the same problem and I noticed that sometimes the baffles or doors on the HVAC system shift around due to no vacuum sometimes while pulling a load up a hill at lower rpm's and heavy on the throttle, so the vacuum could be an issue with other things on the engine.
I have seen a lot of difference in mpg from one tank to the next while driving cross country, so the quality of fuel can have a significant effect, nothing you can do about that except be observant and buy from the place where you get the best economy.
You could remove the front drive shaft, don't know how much that would help, but it's a pretty easy thing to do. However, it's not a very massive shaft so don't think you'd really gain all that much there. That would of course leave you with 2 wheel drive. But, at $6.50 / gal .. I'd be tempted to try anything.
You might also consider altering the shiftpoints of the transmission to optimize fuel economy, or just use a light foot on the throttle and work the buttons to keep the transmixer from continually shifting which can affect mpg.
You could rent another vehicle for the vacation. Mini Cooper or something that burns dirty chips oil! Or take mass transit.

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Suddenly, without warning, nitpik exclaimed (4/30/2005 4:16 PM):

Toppers aren't available here anyhow.

work done on the truck here, there are no Dodge vehicles (aside from those us Yanks brought with us), and even the Chrysler dealer isn't familiar with Dakotas. But maybe they can do a smoke test, and determine if there's a leak. Dunno...

I've noticed that when driving in the US as well (mpg, and how well the truck runs), but my choice is essentially on base (when it's finished) for the cheapest gas (around $3/gal I think) or at places that take the gas coupons (which cost slightly more).

remove the shaft. But thanks for the suggestion.

create my own shiftpoints, my truck's a stick. I haven't changed my shifting style, and it used to get very close to (and occassionally over) 20mpg, so I think my shifting isn't the problem.

Lots less comfortable on long trips, but at least we won't have to take out a loan to pay for the petrol!
Thanks for the suggestions. If we can get more than 15 minutes of sunshine, I can go out and change the air filter, anyway.
I'm currently requesting standard oil (5w30, I think) at changes. Is there any real advantage to moving to synthetic?
jmc

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[snip]

Not unless you enjoy squandering your money.
One of the many "claims" once being tossed about was that w/synthetic you can go longer between oil changes. Well, whether or not you can, it's probably not such a good idea, because although synthetic doesn't break down as easily, it still gets just as dirty/contaminated just as soon as it ever did. Dirty oil is dirty oil.
I've heard equally wild claims that synthetic oil helps get better gas mileage. If it does, the price of synthetic far offsets any incremental fuel savings. To me fuel economy is more about "economy" and the total cost to operate than it is about how much gas I burn getting from point A to point B. Gasoline is only one component of the cost to operate. If suddenly I triple the cost of an oil change it's going to take a *LOT* of fuel savings to recover that cost.
Does your owner's manual say to use synthetic? No, it doesn't. That should tell you something. If it were recommended, don't you think the manufacturer would say so?
Don't listen to the carnival barkers and snake-oil peddlers. Save your money.
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snipped-for-privacy@dodgecity.cc wrote:

gallon (and most places even more), it could actually be cheaper in the long run than dinosaur oil. If you were to get 1/2 mile per gallon better with synthetic (not saying you will, but maybe) and you normally get 16 MPG, then the difference in cost of fuel over 5,000 miles (if that's how often you change oil) would be $18.93 over that distance assuming $2 per gallon. If synthetic costs $3.50 more per quart, and you use 5 quarts, then you would have saved $3 (combined gas and oil) over that 5000 miles. 5000 / 16 = 312.5 gallons = $625 plus 5 quarts oil at $1.50 ($9) = $634 5000/16.5 = 303 gallons = $606 plus 5 qts synthetic at $5 ($25) = $631
As far as owners manuals saying to use synthetic? Late model Dodges do require synthetic in the rear axle if used for towing (at least my owner manual for the 2002 1500 and the 2004 Dakota require that) so it seems that Dodge realizes that synthetic is tougher and holds up better than regular oil in that application. Dodge doesn't require synthetic in the engine, but the benefits of synthetic oil in the engine during cold startups is well known to anyone that has lived in really cold places and tried synthetic. It just flows a lot easier and the engine is more responsive initially with free flowing oil. If your trips are short distance, then I'm sure it would have at least a small impact on fuel mileage.
JPH
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I would like to meet the owner of every gasoline-powered Dodge Ram V8 (5.2 or 5.9) of recent manufacture with unaltered original, street-legal factory engine, transmission, differential & exhaust who gets (long-term averages) 16 mpg. Try 12~13. By your own admission the mileage improvement you claim is hypothetical, based on a "maybe" (your word, not mine). Show us some repeatable/verifiable results on a dynamometer from an independent lab, (not one owned by or working on behalf of the oil manufacturer) with all other things being equal except for an oil change with over the counter, commonly available synthetic crankcase oil and you might be able to sell me on the concept.
I have no argument that the engine may operate a degree or so cooler, start easier in winter and exhibit incrementally less long-term wear, but claiming 0.5 mpg overall improvement in fuel economy (13 vs 13.5 mpg, or in other words a 4 percent improvement) is a bit of a stretch for me.
Of all the "Fuel Saving Tips" (Consumer Reports, April 2005) listed, don't you find it ironic that they of all people -DO NOT- recommend synthetic? In fact CR says, and I quote, "Dont spend extra money on synthetic oil unless your car calls for it." (CR Auto Repair article, October 2002)
Still not convinced? Check out www.fueleconomy.gov Absolutely nowhere on this site is synthetic crankcase oil even mentioned.
Trust knowing if there really was an economically valid reason for using synthetic vs dino motor oil, these people would jump all over it.
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snipped-for-privacy@dodgecity.cc wrote:

WHOA! I wasn't trying to "sell" synthetic motor oil, only stating that you shouldn't dismiss it entirely. Since the person who started this thread has a 4.7 litre Dakota, not a Dodge Ram 5.2 or 5.9, I'm not sure why you threw that engine size in there. In any case, if we were to use lower mileage figures, then a small increase would bring even more monetary fuel savings than the 16 to 16.5 that I threw out for comparison "IF" you were to get any gain in fuel mileage. It appears that more and more auto manufacturers are starting to use synthetic or synthetic blends as original and/or recommended oils.
Mobil 1 website claims the following: "Mobil 1 is factory fill in:
* Aston Martin * Bentley Amage and Bentley GT * Cadillac CTS, XLR, SRX and STS * Chevrolet Corvette * Dodge Viper * Mercedes-Benz AMG vehicles * Mercedes SLR * Mitsubishi EVO * Pontiac GTO * All Porsche vehicles
High praise that speaks louder than words."
(Their words, not mine) My 2004 Ford Focus lists the following in the Maintenance and Specifications section; Engine oil; (Ford part name or equivalent) Motorcraft SAE 5W-20 Premium Synthetic Blend Motor Oil (US)

That's why I used the words "IF" and "MAYBE". I'll let the reader decide if they think they get any extra mileage from synthetics.

If I believed everything that Consumers Reports said, then I wouldn't have purchased a Dodge Ram in 2002 or a Dakota in 2004! (I tried to find the "fuel saving tips" article in the April 2005 edition, but couldn't find it. What page is it on?) Fuel prices at the time the Oct 2002 article was written were less than $1.40 a gallon. Todays higher fuel prices make any fuel economy increases more financially effective.

You're right, the fueleconomy.gov website doesn't mention synthetic oils, but it does conclude that thinner viscosity oils provide better fuel mileage than thicker viscosity oils, and recommends you choose oil that states "energy conserving" on the label. So it seems that they believe that oils can make a difference in economy.

It seems that some manufacturers are starting to lean more toward using or requiring synthetics or synthetic blends, and this will probably increase if the CAFE standards start getting tougher.
Interestingly, the Motorcraft "synthetic blend" motor oils are only about 20 cents more than normal oil at my local Wal-Mart.
For an interesting study titled "substituting synthetic oil for conventional oil" check out this webpage; http://p2library.nfesc.navy.mil/P2_Opportunity_Handbook/6_II_4.html
It's an article about military use of synthetic oil.
JPH
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The April 2005 CR article "Fuel Saving Tips" is in the online version of the rag.

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12-14 highway sounds a bit too low, my 99 Durango 5.9L gets about 16. Anyhow, check out possible conversion to LPG - liquified gas is much less expensive in UK than petrol, and will probably pay back conversion costs in about 20-30K miles.
Peter
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