MPG Cummin's Diesel

[Major Woods]

Re: MPG Cummin's Diesel

In June of this year I purchased a new Ram 3500, Quad Cab, 5.9L Diesel, 6-speed manual, 4x4 with 3.73 gears.
In the first week I put on a MBRP exhaust, Airraid intake. @ 15k put in Mobile-1 motor oil.
The first fill up of fuel got me 20.0mpg on the commute to work.
With 18k on the odometer I am getting avg. 23mpg on the commute to work. 25.5mpg on my last 180 mile highway trip and 15 while towing a 26'WA boat.

All mpg calculations are by hand, the onboard computer does read .3-.5 over the hand method.

Driving a truck with so much grunt is addicting to say the least.

 

[woodrat]

Re: MPG Cummin's Diesel

In most of the fuel economy discussions I've seen on these pages, the fuel economy for gas engines always seems to be posted as a worst case yet the diesel economy is figured at the best economy so those dollar savings are questionable at best.

well, when I posted mine I did not fluff up the diesel mileage. 15-18 is average. the lowest I've ever got in this truck was just under 14, the best I ever got was just over 20. This truck is a 4wd, 5 speed 3/4 ton. And the gas truck I was driving was a 77 powerwagon with full time 4wd, 318 2 barrel and a 727 auto trans. I never got above 9, but never got below 7. It didn't matter if you were full or empty, towing or not.

Obviously, if you were trying to buy a new diesel truck and justify it based on the fuel savings, you would never make the math come out in favor of the diesel. But last I looked, gas powered new trucks weren't exactly cheap either, and no gas truck will ever last as long as a good diesel.

 

[wncrjb]

Re: MPG Cummin's Diesel

OK, here's my math on this........
like I said earlier, I run a 2003 7.3 powerstroke dually 4WD 6 speed manual trans for my business, so I keep exact records for expenses for tax reasons. This powerstroke replaced a chevy dually that has a 454 gas motor with an automatic trans.
I do grading work using bobcat mini equipment so my gross weight is between 18,000-20,000 pounds on a very regular basis, I work in western North Carolina where we are in the Appalachian (blue ridge)mountains so it is also quite steep mountainous terrain.

I just spent this morning going through my records for 2007 to get an exact number on just what my truck has done so far this year.

My diesel went 35,617 miles in 2007 ( so far )
I have purchased 2122.59 gallons of fuel
I have spent $7127.66 on fuel

That averages...... 16.78 MPG
----------------------$.20 cents per mile ( CPM )
----------------------$3.358 per gallon purchased

NOW, looking into my past records when I used my gas powered dually on a daily basis, I figured I had an overall mileage of 8.41 MPG. Given the miles I ran this year that comes out to:

35,617 miles at 8.41 MPG = 4235.08 gallons of gas
The average gallon of gas in area in 2007 was $3.099 ( according to the gas receipts for my car ).........

That means I would of used $13,124.50 in gas.
OR $.37 CPM

That comes out to I saved $5996.68 in using the diesel over the gas for the year, ALSO 17 cents per mile saved.
This is not to mention the extra torque provided by the diesel, the better breaking system, and the better handling characteristics etc.

On the maintenance side:
I change my oil at 5000 intervals at a cost of $51.00. That comes out to about $.01 a mile ( penny a mile )

My gas motor truck:
changed oil every 3000 miles at a cost of $30.00 ( 8 quart oil pan ). which comes out to about $.01 a mile ( penny a mile )

Now to be fair, the diesel does need a new fuel filter every THIRD oil change which costs me $12.00 for the filter and another 15 minutes of time.

To sum it up....FOR MY APPLICATION, a diesel does pay for itself, the proof is right there.
If I didn't have to haul this equipment every day, I'm not sure if I would get a diesel, they are somewhat noisy and the fuel does stink.

And when I was looking for a diesel truck, it didn't matter to me of the make, the powestroke, cummins and duramax all are superb motors ( well, the early 6.0 powerstrokes had problems) and will last about forever with good maintenance. I just got a good deal with the truck I got.

All I can say if from my own experience with my truck is, it now has 176,000 miles and other than routine maintenance, it has been flawless, and this truck does get worked pretty hard on a daily basis.... granted it's not to say next time I pull out of my driveway I won't run over my crankshaft, but that's something that can happen to any vehicle.
AND, yes, it does get my 18 foot boat to the lake pretty easy LOL.
I hope I don't start a war with this post but I figured I would post some exact number from MY OWN experience on this topic. May you all have a great holiday season.

wncrjb

 

[jay_merrill]

Re: MPG Cummin's Diesel

You are doing very well on mileage with the Powerstroke, considering the weight you are pulling. My experience with a 250, auto and a 550, 6 speed, running at similar weights, was not as good. I will say, however, that the six speed in the 550 is not the same one that you have in the 350 and the final drive ratio probably isn't the same. That might account for the difference.

That said, in commercial use, the argument for a diesel is much stronger. Running a gas engine at the weights that commerical users often do, will put a lot of strain on them and reliability becomes a factor in addition to fuel use. Just knowing that your rig is going to get up and go to work everyday is worth the price of the diesel motor because it isn't making you any money sitting in the shop.

Your motor will probably outlast your tranny by a long shot, at least that has been my experience. Powerstrokes like to eat a turbocharger now and again, plus a few other problems, but the basic motor is pretty tight so you should enjoy long engine life overall. If you are driving the truck yourself, with the care that the guy who has to pay to fix it usually does, you might do ok on the tranny too. Just bear in mind that the 7.3 is a big motor for the application that Ford applies it to in a 350, so it gets easy to forget the strain on the tranny, when climbing a hill that doesn't bother the motor much.

 

[External Combustion]

Re: MPG Cummin's Diesel

In my take of the situation, it all depends on why you want the truck. Do you just need good sound transportation for you and your goods at the least cost per mile or are you wanting aminities up to and including the "look at me" stuff. Both extremes are nobel, it is just dependent on your desires.

If the lowest cost per mile is the answer, then finding a good used diesel stands a good chance of being the answer. An ex rich boy's toy can usually be had at a substantial discount, along with goverment and business auctions. I needed a medium duty truck and bought one for $2600 from a local city auction. Ten years later and close to 90k miles, I have had to put on an air compressor, 5 sets of brake diaphrams and a windshield wiper. I routinely use it at over 25K pounds, sometimes up to 40K. It gets 10 mpg. Though pickups usually bring over four times this amount, you can still shock yourself by reading what little your local goverment gets for their used equipment on sealed bid.

If going in style is what you want, all that is neccesary is to decide how much style you will afford. If new is important, then the diesel over gas argument is almost moot as you will probably not hang onto it long enough to see a dollar difference. A big gasser will easily handle the 4k trailer load. If you don't like the high rpms over the mountians, just slow down. Put the tranny in the gear that is easy on the engine and watch the countryside. Enjoy the trip! Personnally, the older I get, the more I like style!

I have not found that big of a difference between the cost of diesel and gas engine maintenance.

Good luck on your decision.

 

[wncrjb]

Re: MPG Cummin's Diesel

You are doing very well on mileage with the Powerstroke, considering the weight you are pulling. My experience with a 250, auto and a 550, 6 speed, running at similar weights, was not as good. I will say, however, that the six speed in the 550 is not the same one that you have in the 350 and the final drive ratio probably isn't the same. That might account for the difference.

I really can't complain about my mileage with what I'm using the truck for. Then again, I'm the only one that drives it and I'm very fuel conscious. I thought the 550 had the same trans (ZF-6) as the 350? I'm sure we have different ratio's in the rear end. I know mine is a 4.10 and you are probably around a 5.56.(?) My friend has the same truck as mine but with 3.73 gear, and averages 3 MPG better than me with his, hauling a 32 foot camper.

I was reading on a diesel forum about getting the best mileage out of a diesel ( which gets flamed like asking "what is the best oil to use" on this forum LOL) and with all the responses, one man put it best......... it don't matter what cab you have, trans, gear ratio, whatever.... keep your cruise RPM around 1700-1800 RPM to get the best MPG with a powerstroke. The only problem with that on my truck is, 1800 RPM is 58-60 MPH. It makes for a slow ride down the interstate.

wncrjb

 

[Silvertip]

Re: MPG Cummin's Diesel

We are getting way over the top on the original posters question. He's pulling a 4000# boat so the first element to consider is do I really "need" a diesel? No -- he doesn't. Then one must consider do I "want" a diesel. If the answer is yes, and you can afford it by all means get a diesel. But for those of you who are considering a a "first diesel" be aware that they like to be started, left running, and not started, run three blocks to the grocery store and shut off. Started again in an hour only to repeat the cycle. They simply don't like that. But if that's your bag, go for it. Now then - since fuel economy seems to be an issue rather than outright towing, consider this. A GM flexfuel truck will get 14 MPG on E-85. Over 100,000 miles that truck will consume 7142 gallons of fuel. As I went past my local station today the price for E-85 was $2.20 so the total gas bill for 100,000 miles is $15,714. I should point out here I'm using the GM "city" rating for fuel economy -- not highway. And yes -- I am aware mileage is less on E-85 as I use it which is why I used the "city" MPG. Since every diesel owner here claims to get 18 MPG lets run that (again). Over 100,000 miles the diesel burns 5555 gallons of fuel at $3.60 per gallon which equates to $19,999. Looks like a difference of roughly $4,200 in fuel with the truck that burns corn squeezins. Obviously E-85 is not available all over but I made a nine state trip in late August/September and was able to find E-85 nearly anywhere I went. Prices of E-85 also vary all over the map and in some cases its actually more expensive than gasoline. My experience is that if you have a flexfuel vehicle, E-85 needs to be a minimum of 30 cents/gal cheaper than regular to break even. Anything more than that is money in the bank.

 

[woodrat]

Re: MPG Cummin's Diesel

can't get ANY internal combustion fuel in these parts for less than $3.00/ gallon. Mid grade unleaded is $3.20-3.30 around here, diesel is $3.45-3.60. Adding another $1.00/gallon would turn your $15,714 into $22,856, almost a 50% increase.

I do think that the diesel will last way longer, do more work and, in the case of my all mechanical 6 cylinder Cummins anyway, cost less to maintain. I don't think you could put 270,000 miles of towing and hauling on a early 90's 454 and not need any major engine work. All bets are off on the newer, computer controlled diesels, though. The latest generation of Navistar/Powerstroke engines has suffered from all kinds of fueling related troubles.

I do use my truck almost exclusively for towing and hauling, not as a grocery getter.

 

[dbric36]

Re: MPG Cummin's Diesel

Well not everybody can get e-85 or use it. I never seen it advertised. I use diesel at 3.19 gas is 2.92 all summer diesel was .30 less than gas. I got 13 mpg ave. pulling my Sea Ray 270 WE I see on trailerboats that the new tundra get 8.1 mpg pulling a Sea Ray 220 sundeck. I wonder what it would get pulling my boat?

 

[tommays]

Re: MPG Cummin's Diesel

In my neck of the woods the SALT will eat the body OFF (SEA AIR and ROAD SLUSH) long before you wear it out unless you put on the miles really FAST




Tommays

 

[buckstop108]

Re: MPG Cummin's Diesel

I can't tell you all how much I am enjoying all this info. Just when I think I have it, somebody brings up a good point. Just to clear one thing up as External Combustion mentioned and it was mentioned one other time. I AM NOT THE GUY "HEY LOOK AT ME". I am the guy that really doesn't like buying a truck every few years and I am the guy that wants my truck to perform the wat it was suppose to. I also would like the truck to go when I say go. I'm not rich far from it. I also am not a grocery getter. I may have a tendenct "to drive a tack with a maul" I love that saying Thanks Silvertip. but I do understand the importance of "not needing " and "wanting" .
As far as slowing down when the RPM's go up. You obviously have never traveled Interstate 87,81,95.287,80 278,84,78,90,390 just to name a few. If you did you would know slowing down is not a good thing. The trucks I mean the ones with 18 wheels like to go. They really don't like going around and if you have ever been in a snow storm of heavy fog then you can appreciate keepinhg up with the flow of traffic. I do not want my SS prop bent. There is nothing worse then having that big boy on your A_ _ at 3AM. So when I tell my truck to go I want ity to go. Diesel or Gasser. So I guess the question here is if I have a Dodge 1500 4x4 Quad Cab wit the towing package and the 3:7 rear 5.9 L V8. Steping up to the 2500 will it get me want I want, which is to go when I say go.

 

[lorenbennett]

Re: MPG Cummin's Diesel

Hello everyone. Was browsing and saw this post and since I have a 07 2500 4 x 4 mega-cab with cummins I thought i would give you how mine runs. I traded from 2wd to 4wd and saw a 3-4mpg drop in performance then I added the superchips and i am getting around 20mpg and 13-14 towing a 03 searay 260 sundancer. I was pulling this boat with originally with a 2wd hemi powered 1/2 ton quad cab and the mileage would drop off to 4-6mpg on long trips. Then we traded to the 2wd 2500 but did not like it so traded back in for th 4wd. Best thing I ever did. Does it of set the cost of diesel (??) but the power and ride far offsets the cost. How can I put a cost on safety and comfort. Icase the post is confusing, yes we trade an 05 1500 to 06 2500 2wd to 07 4wd. Now we are happy.

 

[Wotam]

Re: MPG Cummin's Diesel

>"You flunked the math test. "

Not really.

Using identical costs per gallon is an approximation and was deliberate based on the uncertainty of relative gas/diesel prices in the future. Around here right now diesel is about 4% more than gas. This is allegedly due to a 'short term' problem in diesel refining capacity due to 'new ' federal regulations. (Yah, the 'new' regulations that were announced nearly 10 years ago).

Over a 10 year ownership run, the diesel premium may get higher, or (what I think is more likely) it may swing back where it belongs with diesel being .30 per gallon less.

Ok, so let's run 100% real numbers... using the latest California fuel price reports. Found here: http://tonto.eia.doe.gov/oog/info/gdu/gasdiesel.asp

18 mpg 100000 miles - 5,555 gallons X $3.42 = $18,998
12 mpg 100000 miles - 8,333 gallons X $3.28 = $27,332

Diesel savings: $8,334

Now let's do something scary... say the price of fuel goes up 30% in the next 10 years (This very easy to visualize, it likely will be a lot more).

18 mpg 100000 miles - 5,555 gallons X $4.44 = $24,664
12 mpg 100000 miles - 8,333 gallons X $4.26 = $35,531

Diesel savings: $10,867... the higher the prices, the more the savings, provided the gas/diesel price ratio remains somewhat constant.

As for the argument that a diesel engine is more expensive to maintain? The only significant difference I find in 'routine' maintenance is that most diesel engines have bigger crankcase volume... that's about it. I put in 3 gallons instead of 1.5. Fuel filter every so often in both, air filter every so often in both. Beyond 150,000 miles, the diesel starts to leave the gas engine in the dust as the a big-displacement gasser is going to be needing engine work while the diesel is just 'broken in'.

 

[Silvertip]

Re: MPG Cummin's Diesel

In areas of the country where the two fuels are nearly the same cost there is no disagreement on fuel cost differential. The higher mileage vehicle wins. In my neck of the woods diesel is far more expensive than regular, and E-85 as was mentioned earlier is $2.20 and is always about 60 cents/gallon cheaper than regular and a buck-plus cheaper than diesel. If I needed a new truck it would be a flex fuel vehicle. My car is run almost exclusively on E-85 (and it smells nice too).

 

[jay_merrill]

Re: MPG Cummin's Diesel

If you get lucky and nothing of consequence breaks, you will remain happy. If you are not so lucky and have to replace something like a turbocharger, you won't. I would say, however, that if someone truly plans to keep a truck beyond 150,000 miles, the diesel has definate advantages. The problem is that most people don't keep a vehicle that long because every thing a else tends to start looking a little rough. I think we all know the scenario pretty well .... truck paid off? Good, time for a new one.

In the end though, its really a matter of what fits the needs of the indiviual and, on that basis, no one here is wrong.

 

[SpinnerBait_Nut]

Re: MPG Cummin's Diesel

It's what a person wants that matters, IMO.

 

[QC]

Re: MPG Cummin's Diesel

Oil cost is higher too . . . The only correct way to evaluate this is to compare putting that premium in some sort of investment. That loss of cash use is relevant too.

BTW, I am a diesel lover, I have sold them my entire career since I was 18; I am 48 . . . but rarely do I believe that diesels actually pay for a non-commercial customer. As some have said the argument is not always economics, and that is OK, but the economic discussion needs to be an economic discussion and for that you must evaluate the cost to use additional cash for whatever time 100,000 miles means to you. AKA NPV

Edit: Spinner, that's what I meant by the discussion wasn't always about economics. I agree. Posting before I saw yours . . .