Gas vs. Diesel - Life Cycle Cost Analysis

[FrogPond]

The Rogue's Dodge thread got me thinking...

Help me set some values for a life cycle cost analysis between a gas and diesel rig. Same make, model & options.
Annual usage = 20,000miles

I will adjust these values with input from you guys...

Oil changes @ 3000mi
gas = $4/gal
diesel = 4.50/gal
(also assume fuel prices go up 3% annually)

Purchase price:
Gas $35K
Diesel $40K

Gas mileage:
Gas 13mpg
Diesel 16mpg

Oil Changes:
Gas $30
Diesel $100

Repair Costs (annual average)
Gas $100
Diesel $200

Useful life:
Gas 6yrs
Diesel 10yrs

Salvage Value:
Gas $10,000
Diesel $10,000



I won't run the analysis until we get the numbers tied down...

[lentz]

I have a diesel and i do like it but the cost of parts is out of this world compared to the gasers.

[hot wire]

Oil Changes:
Gas $30
Diesel $100

Repair Costs (annual average)
Gas $100
Diesel $200


I would sharpen your pencil for these two figures. Oil changes are around $70 for diesel.

The repair, my diesel trucks have been darn reliable. How did you come up with the $200 vs $100?

Tom

[FrogPond]

Originally Posted by HewesFisher

Oil Changes:
Gas $30
Diesel $100

Repair Costs (annual average)
Gas $100
Diesel $200


I would sharpen your pencil for these two figures. Oil changes are around $70 for diesel.

The repair, my diesel trucks have been darn reliable. How did you come up with the $200 vs $100?

Tom

Just guesses at this point...my truck is gas. help me out with the #'s...if you spend $2k on repairs for a diesel rig over 10yrs, then the annual amount is $200. Is it less? My gas repair# may need to be increased...

$70 for oil changes...I will change that.

[ICHTHYDEMON]

Originally Posted by FrogPond

Just guesses at this point...my truck is gas. help me out with the #'s...if you spend $2k on repairs for a diesel rig over 10yrs, then the annual amount is $200. Is it less? My gas repair# may need to be increased...

$70 for oil changes...I will change that.

Since a diesel has a factory warranty of 100K (on the engine) you really aren't incurring any repair costs that wouldn't be the same as on a gas truck. Things like brakes,transmissions,wheel bearings,would have to be relaced regardless of gas/diesel.

Oil changes for a diesel can run $100 if you have it done at a dealer. I can change mine for about $35. The Fleetguard filter runs $10 and 3 gallons of oil at about $8 a gallon.

An oil change in my gas rig ran about $20.

[ICHTHYDEMON]

Oil changes will need to be looked at also. I don't think Ford,GM or Dodge recommend anything less than a 5000 mile OCI.

My Cummins has a 7500/15,000 OCI. Not many people fall under the stipulations for the 15,000 mile OCI though. I'd bet 95% will need to use the 7500 mile OCI.

[AtItAgain]

I have a 2002 Ford superduty with a 7.3 diesel. Other then regular oil changes I have had very few problems with it in the 6+ years I have been driving it. I have 65,000 miles on it. It has tow a lot. Travel trailer, 38ft fifth wheel, and an 11'6" camper.

I have had two problems with it in that time.

1. cam positioning sensor when out. I was hooked to my 5th wheel at the time, so I fixed it myself. Cost $110.

2. One of my intercooler tubes came off. Cost $150. Wish I would have figured that one out myself.

I have some Banks components on my truck and if I am running hiway unloaded I get close to 20 mpg and I do not have a chip or program.

[Reelentless]

99 7.3 Powerstroke with 265,000 miles.

So far:

water pump - $300
O rings for the HPOP - $250 (mostly labor)
3 cam sensors - $240
oil change every 5k miles - $60
fuel filter every 10k miles - $30 each
radiator flushed twice - $100

Thats it.

[FrogPond]

Probably the most important aspects to this are...
Purchase price
and
Service life

any input on these?

[Reelentless]

Back in 99, the powerstroke was a $4500 option over the V10. Now I think its close to $8000. So the same truck would be $8000 more than the V10 version. You will probably get 1/3 of that back in resale, assuming both trucks have the same mileage.

Service life really depends on how well its taken care of. I'd estimate twice the life for a diesel on average.

[EvilD]

I am running full synthetic Amsoil in the crank case and Transynd (Allison) in the trans. OCI is 10k, Trans is 50K. Oil, fuel, and spin on trans filter every 10K. I spend about $125 every 10K. I get about 21-22mpg on the highway and 17-18 in traffic. My initial cost of the diesel will be repaid upon resale.

One thing is for sure. When I romp on it and spew black smoke on the idiot tailgating me, every cent I have put into my truck is paid off with interest.

D

[Tilla]

The oil changes for synthetic for my gas Explorer are over $60 at Oil Can Henri's.

It's not going to be easy.

How are you going to measure the feeling you get when that diesel rumbles to life!

[cavdad45]

A diesel is just getting broke in while the gass car is worn out. Sorry, 10 years is the life of a diesel only if you crash into something, otherwise they will run 15-20 w/o major repairs. They are bullet-proof.

[haringsjosh]

2006 Dodge Turbo Diesel. 35,000 miles now, Oil Changes run me about 60 at the dealer. Other then basic maintenance i have had 0 problems with my truck. One thing that does cost a little more is the tune up.
My 30,000 was $990, 60,000 will be more like 1200.
The last truck i had was a 99 dodge diesel. "Late Lemon" is how i refer to it. Had this truck the entire life, no problems until i hit about 120,000. Then everything came into play. First, Rotors (Normal), Fuel Filters , injector quit, glow plugs and something to do with seal on glow plugs. The repair on that truck cost me apx 5k within 4 month period. Had all sorts of smaller problems however, i still will stick with a diesel. Love the power, love the truck and i love Cummins Diesel. Over the long run i think a gas truck would be a little cheaper however you have many more benefits from a diesel. Banks exhaust and new chip brings gas mileage in a diesel to apx 25mpg which i have never seen a gas truck get. Please support bio-diesel.

"If everyone had switched to bio-diesel, would we be in Iraq?"

[HuntnCoug]

Oil changes cancel each other out, changes on a diesel cost twice as much as a gas rig but you can safely go twice as long between changes. I have a 96 cummins with 160,000 miles on it I have tuned it up once, replaced the breaks twice, and put two sets of tires on it and that is it.

[WaterDog]

Josh,

Do your own oil changes, $50-60. If you get an auto tranny, you'll want to service it every 25 - 30K miles. There are minor repairs but most you can do yourself to save some $. There are some great websites out there that can walk you though most things. I've saved $100's if not a thousands doing stuff myself.

Frankly, unless your pulling a fairly large load, say something over 6000#, I'd go with a gasser( And yes I have a diesel.) I'm not so sure it pencils very well anymore. Maybe with driving 20K a year it will. I'd be interested in seeing your analysis when done.

I have an older rig (2000 Ford) and with the new ULSD fuel I have lost 2mpg towing and about 1mpg on the hwy. Replacement cost is outrageous. I've been crunching some numbers as well and will soon be making a change. The diesel is going to be parked.

[Silver Hilton]

Originally Posted by cavdad45

A diesel is just getting broke in while the gass car is worn out. Sorry, 10 years is the life of a diesel only if you crash into something, otherwise they will run 15-20 w/o major repairs. They are bullet-proof.

Is there enough data to draw any conclusion? Aren't the oldest powerstrokes something like 8-10 years old? I've always been suspicious of claims about the longevity of consumer grade diesels, after the GM debacle in the 80's, but I honestly don't know the answer.

[huntercgr]

1) Under average use, I'd change the diesel oil changes to: every 7500 miles.

2) Oil changes at a Ford dealer were $65.

3) Repair costs? Not too sure you could factor this in w/o real hard data. I've spent $0 on repairs after almost 4 years.

4) Useful life: Gas, I'm guessing closer to 8 years, diesel 12-15 years.

5) Salvage after above years: Gas maybe 5-6K....diesel 10K

[Amahnee]

I have an '01 Dodge cummins. I've been getting my oil changed at a dealer for $35. Good deal! Other than my transfer pump going out at 71k and replaced for $750, I'm good.

[fish_on]

Originally Posted by Silver Hilton

Is there enough data to draw any conclusion? Aren't the oldest powerstrokes something like 8-10 years old? I've always been suspicious of claims about the longevity of consumer grade diesels, after the GM debacle in the 80's, but I honestly don't know the answer.

The original powerstroke 7.3L came out in 1987 it went direct injected in 94. The original 7.3L is still considered one of the most durable consumer diesel engines.

I would also agree with the oil change interval being 5-10K, 7500 seems a good compromise. If all heck hits the fan, diesel will be easier to find than gas, and you can run bio in a pinch.

[ORhunter]

I've got an '05 GMC DruaMax and paid for one transmission service which was fairly cheap at the dealer. Due for the second now which I'll do myself and save a little. Oil changes are under $30 every 3/4000 and that is it. Fuel at 17 mpg does cost a bit but I make up for that by doing the maintenance myself.

[CVmustang]

Based on fuel mileage alone, here is my experience. My 2005 Super Duty 6.0 Diesel got 15 mpg, my 2007 V 10 gets 11 mpg. With fuel prices of 3.25 for gas and 3.75 for diesel, thats .29 per mile for gas and .25 per mile for diesel.With a diesel engine costing about $8000 more, you would have to drive about 200,000 miles to get to the break even point. Both engines are great, the diesel pulled my 10k pound trailer up hills a little better, but I love the instant throttle response of the 30 valve V10 at take off and for passing .

[Dinikin]

Most importan is $$$$$$PG. Don't you think?
I am not saying MPG since you need to include all the related costs of owning a vehicle.

Originally Posted by FrogPond

Probably the most important aspects to this are...
Purchase price
and
Service life

any input on these?

[ICHTHYDEMON]

Originally Posted by FrogPond

Probably the most important aspects to this are...
Purchase price
and
Service life

any input on these?

My '07 Dodge 4x4 has basically every option other than navigation and leather. I don't remember the exact price,but it was $34k and change.

Service life on the Cummins is rated at 350k miles. Thats the number Cummins puts on it. Service life on the Duramax is 200k,again,the number GM puts on it.

Ford doesn't have a stated life expectancy.

The only gas engine that has a rated life span is GMs 8.1 liter big block. GM rates the 8.1 as having the same 200k mile life span as the Duramax.

[Dinikin]

CVmustang,
What kida mileage did you get pulling 10k trailer?
Do you have numbers for both trucks?
Fried of mide pulled 6K trailer with his F350 V10, and said he got barely 8 MPG.
With my 7.3PSD I get about 12 MPG towing same weight.

Originally Posted by CVmustang

Based on fuel mileage alone, here is my experience. My 2005 Super Duty 6.0 Diesel got 15 mpg, my 2007 V 10 gets 11 mpg. With fuel prices of 3.25 for gas and 3.75 for diesel, thats .29 per mile for gas and .25 per mile for diesel.With a diesel engine costing about $8000 more, you would have to drive about 200,000 miles to get to the break even point. Both engines are great, the diesel pulled my 10k pound trailer up hills a little better, but I love the instant throttle response of the 30 valve V10 at take off and for passing .

[Bobberman]

Diesel rigs are heavier and harder on brakes and tires in my experience.

[Amahnee]

Hard on tires yes. I don't use my brakes.

[Lead Bouncer]

Originally Posted by FrogPond

The Rogue's Dodge thread got me thinkin



I won't run the analysis until we get the numbers tied down...

I havent read anything about hauling needs, size or 2x or 4x

[Flatfish]

I have aPSD 7.3 with 130k on it.

It ate a tranny at 80k.

Other than regular maintence, it has been prefect.

I figure tires and brakes are generally a wash, as all rigs will need them at roughly the same interval.

In the not too distant future, I will buy a third rig for my wife to drive, so the diesel will sit unless something heavy is involved. Replacement cost is too great at this time to not extend life by several years.

I figure 250-350k before it iss too much of a headache to justify fixing anymore. I drive 40k a year for work. Fun and games another 10k a year. The diesel is much cheaper when I would have to replace a gas vehicle somewhere between 150 and 200k miles.

If I did not tow heavy(5000k minimum) pretty regular, a Toyota Tacoma would get the nod. Lasts almost as long, much cheaper to buy and operate.

[SeanD]

Originally Posted by fish_on

The original powerstroke 7.3L came out in 1987 it went direct injected in 94. The original 7.3L is still considered one of the most durable consumer diesel engines.

I would also agree with the oil change interval being 5-10K, 7500 seems a good compromise. If all heck hits the fan, diesel will be easier to find than gas, and you can run bio in a pinch.

I dont think thats right. The powerstroke came out in 1994. The previous indirect injection engine was not a "powerstroke". And I think it came out earlier than 1987, my dad had a 1985 6.9 IDI that he sold with nearly 300k on it ten years ago. I wouldnt be suprised to see it still on the road.

I agree the useful service life of the engine is greater than 10 years for the diesel, but its greater than 6 fo the gasser also. Thats 200k for the diesel and 120k for the gasser at 20k/year. Seems really low.

I drove a 1993 7.3L for 8 years and it was a great rig, reliable and low cost/mile (except for the auto trans $$$). With what a new one costs + fuel I decided to get a toyota tacoma to replace it and believe it will be cheaper in the long run.

[FrogPond]

ok, so I am going to delete the repair values

how much should I expect to get (salvage value) out of a 10 year diesel truck, say the purchase price was $47K?

I am going to set a life of 10 years for the diesel and 5 for the gas. These are not going to be the entire serivce lives of either rig. So the salvage value needs to be close.

I tried looking up 10yr old diesels on autotrader but I am not having much luck.

[Reelentless]

My 99 Powerstroke is a Lariat Crew Cab which has almost every option on it. I bought it for 35k and its worth about 15k.

[FrogPond]

A 5yr old ford gas averages $17K
A 10 (9 since all I could find were 1999 models) averages $13K
same criteria all I changed was age and fuel type.

So my revised criteria are as follows:
Purchase Price:
G $37K
D $45K

MPG
G 13
D 16

Maintenance:
Oil, Filters, tune ups
G $100/6000 mi
D $200/5000 mi

[Hogmaster]

Originally Posted by FrogPond

I tried looking up 10yr old diesels on autotrader but I am not having much luck.

Maybe that is because no one with a 10 year old diesel is willing to part with it? They certainly aren't in the junk yards.



This is interesting stuff. One thing, if you are driving 20K annually, how many need a big truck for all of that?

Seems most people anyway would buy a big hualer for their RV and outdoor usage and the annual mileage would be much less. 20K like Kyle drives might be usual for Eastern Oregoners, or rural guys, but why commute with it?

And if that is true, does a 350K 30 year old rig make sense? My 95 Tahoe (gas) just looks old these days, but since it only has 96K on it and mainly sits around waiting for me to occasionally yard the boat out, I can't rationalize replacement (or afford it). I suppose after some point in time it becomes "cool" again, right? Like an old Woody or panel van?

I know this doesn't help the analysis, but other than towing needs, I still wonder if the additional up front pays off for most...

[Flatfish]

Hog-It depends on how much you drive, and how much/how often you tow.

My present work trailer is about 7k gross. It will morph into 10k or so in the next year or two. Here is where the diesel earns it keep. I almost pity the transmission.

I know a couple guys with 350k plus on post 2000 psd's. Both have stickshifts. Both drive 70k a year or more. Both swear they will never own a gas motor again.

Last year, out Ford was draggin sumthin around for abut 9500 miles. And last year was a slow year as far as fishin goes. We could easily add 3-4k a year on that during a heavy fishing/hunting year.

If you only use it to tow the boat on weekends, I agree with ya. Pretty expensive to own for a daily driver.

[98ramtough]

I drive a 2007 Dodge 4x4 quadcab longbed with the automatic. I paid $34k for this truck 8 months ago. I have 36k miles on it. I get 20-21 mpg empty, and 14mpg pulling my 6k lb boat.

If you compare this to a gas rig, you will pay $6k less for the gas rig, but get that $6k back when you trade or sell it.

I change my own oil, but I pay $6 for filters, and $11 for a gallon of delo 400 oil.

So I come up with $39 for an oil change with fleetguard filters. I change my oil every 5K and by the book they recommend 7k. You can run the oil a little longer in diesel trucks since they take a lot more oil. The cost about washes on oil changes cause you can run them twice as long.

In the end it comes down to people defending what they own. I drive a lot, 36k miles in 8 months. I tow a lot. Keep them for 200k and you will pay back that $6k and then in return get that much more out of it when you sell it...


All the gas guys will disagree, but thats ok, most of them REALLY want the power and mileage of a diesel, they just didn't want to foot the extra money up front to get it.

[FrogPond]

Running 2 iterations of the analysis (to account for the minimum one replacement of the diesel) the analysis time is 20yr. Assuming a "real" discount rate of 6% (nominal - inflation) and an 3% annual increase in fuel costs




Option A (Diesel) is the least expensive option in this scenario by almost $10K. If the life of the gas rig is extended to 10 yrs and the salvage value drops to $9800. here is the result:



At 9 years the Diesel still wins...by $84.67

[FrogPond]

I did not start this thread to be a "mine is better" debate. I wanted to run the analysis and use "decent" numbers. These types of analysis have real world merit if you can get the assumptions close.

[Herring Problem]

I currently have a 2005 Dodge 2500 Heavy with 5.9 and auto tranny with the 3.73 gears. Can pull up to 13.500 lb trailer.

I traded my 1999 dodge 2500 with 5.9 and auto with 3.55 gears with
169 ooo miles on the truck for the 2005. The dealer gave me $23,000 for the truck to trade.

I originally paid 21.500 for the 99 truck with 69,000 mileson her, drove it for three years for 100,000 miles and made money.

Repairs consisted of Brakes 1000 bucks. Replaced rotors and drums .

Never had one minutes trouble with the tranny or engine. Just routine service.

5000 oil change 60.00 bucks

30,000 once a year tranny service 79.00 at amaco

Tires- 3 sets

That was the extent of my diesel cost to run for 100,000 miles over 3 years.


2005 cost

oil change is 69.00

fuel filter 14.00 replace myself dealer wants 85.00 to do it.plus filter.

30,000 miles replaced the michelins with yokohomas 10 ply tires $700

My gasoline trucks never got more than 17 mpg- F250 with 460 4x4, pulling boat 9mpg.. Always lowest book for trade in.

My diesel is sitting in the carport- I'm driving my 2000 mustang to work now. She will come out to play in May for the halibut opener. At least she has a full tank right now.

[98ramtough]

People always seem to miss the fact that you pay more upfront, but they hold the value very well!

I had a 98 that I paid 18k for with 60k miles on in 2002. I traded it in 2006 with 160k miles on it and they gave me $14k in trade, probably could have sold it outright for $16k. With that truck I put 100k miles on it with nothing more than a $70 oil sending unit and regular oil change intervals at 5k miles and fuel filters at 10k miles.

[WaterDog]

Using trade in values is not a good measure of worth since some places monkey with the "values". They keep the price high and give more on trade in. It's not a real present worth. I know a couple of trade in's I've done have a lessor selling price than what they gave me for the trade.

How do you factor in the cost of having to replace a rig? I'm in the same camp as Flatfish and Hogmaster. I would not and could not afford to replace my current truck based on todays prices. If you can extend the life of a vehicle by 5 or 10 years, by getting a "commuter" car, how much further ahead would you be? Or are you?

[FrogPond]

I used the average value I got off a quick search on Autotrader. Not a very scientific look, but it works.

I don't think very many people use a vehicle until it's dead. So it is more a question of when do most people "upgrade". The replacement cost is factored into the analysis, that's why it is performed over a timeline that includes at least one replacement of both options.

Assume the commuter car would decrease the miles by half per year, so the fuel and "maintenance" will drop, the "salvage value" would drop (because the truck is now 15 yrs old instead of 10. The result is another 5 years of service for about a $3,000 increase. (total is $155,107 vs. $152,356)