6.0 vs 6.6 fuel economy?

Prokopchuk_9 · July 28, 2013

I have a 2011 6.0 gas hd2500 that gets pathetic mileage and I had been thinking about going to a diesel. I recently drove by myself from St Louis to Baltimore....16 hours. Being board, i started keeping track of the difference in cost between gas and diesel fuel as I passed the truck stops on the hiway. I noted the difference in price at 104 truck stops from Indiana to Maryland. At a few, there was no price difference, and the worst was $1.04 difference, gas always being cheaper. The overall average for 104 stations was $.55/gallon, diesel being higher than gasoline.
Having several friends that have diesel trucks (mostly Fords and some GMs and one Cummins), I took a poll of 12 people to get their real world mpg numbers.

My 6.0 gas engine gets 14 mpg average and 7 towing. The average for 12 diesel trucks was 17 mpg average and 11 towing.

I used an assumed cost of $4.00/gallon for gas and $4.55/gallon for dieslel and ran a spreadsheet for both.

Using 20,000 miles as a base for average mpg, a gas motor at 14 mpg the total cost at $4.00 is $5714.29. A diesel at 17 mpg the total cost at $4.55 is $5352.94. Advantage diesel for $361.34 after 20,000 miles......supprising??

Using 4,000 miles as a base for towing mpg for a summer season, a gas motot at 7 mpg at $4.00 is $2285.71. A diesel at 11 mpg the total cost is $1654.55. Again, advantage diesel for $631.17......another surprise?!?

Given the maintenance costs of a diesel (oil filter for my 6.0 at Oreilly is $4.29, a oil filter for a Ford diesle is $23.00 as one example) plus the $6000-$8000 extra initial cost for a diesel motor, I absolutely do not see any financial advantage for owning a diesel over 20,000 miles. Even extrapolating the average mpg five time for a total of 100,000 miles, the diesel advantage is less than $2000.....so, it would take 400,000 miles to offset the cost of a dieslel engine's original cost, again not comensating for increased maintenance costs.

Having noted all of this, I know a diesel pulls better, less shifting, etc., etc., etc. But, i keep seeing and hearing how much cheaper diesels are to run. I am not so sure.

I understand that some folks get better diesel mileage, and some get worse. The info I used came from folks that pull 7000-9000 pound trailers.

After this research, I think I will be keeping my gas truck. I tow 8000+ pounds at 60-65 mph and it does fine.....

Interesting read, but you didn't take into account resale value. When you go to trade it or sell it, it will be worth much more than the gas truck. 06-07's still go for 30k around here, 06-07 gasser maybe 15-20 with equivalent mileage. That initial cost of te diesel shouldn't be taken into consideration cuz you will get much more money come trade. Just IMO.

zogg · July 28, 2013

I am not sure that resale value should be considered in long term costs.

I fully agree that a diesel truck will bring more money, but it also costs more money....hence a wash.

It reminds me of the time a dealer told me he would have been able to give me $1000 more for my trade in if only it did not have a manual tranny. My response was that I saved my $1000 on the front end when I bought my truck by not spending the money for an automatic tranny......same for a diesel, I believe

sdeeter19555 · July 29, 2013

I am not sure that resale value should be considered in long term costs.

I fully agree that a diesel truck will bring more money, but it also costs more money....hence a wash.

It reminds me of the time a dealer told me he would have been able to give me $1000 more for my trade in if only it did not have a manual tranny. My response was that I saved my $1000 on the front end when I bought my truck by not spending the money for an automatic tranny......same for a diesel, I believe

You get some of that initial investment back, but not all of it. I've bought/sold/traded many diesel-powered pickups and not one did I get all that much more than I would have with trading a similar model gasser. For the upfront cost, you only see a fraction of that at the trade in; just like the rest of the truck.

And one thing that has been overlooked is that a new diesel also requires DEF, which is an added cost...on top of the premium price for fuel in this area.

They have their place in the commercial world, but for the average Joe; you either want one or you don't. I have been down this slippery slope many times, and no matter how you spin the $$; its a wash in the end in today's market. Maybe for some of those that have cheaper diesel and put loads of miles on in a year; but for those of us that have nearly $0.50 more per gallon for diesel; its not.

Don't get me wrong, when the Cummins hit the market in 88/89, were getting 20 mpg or more, and the price of diesel was 25% less than gasoline; they were definitely more economical. THEN it made sense and these arguments had lots of merit.

From my experience so far (between the last truck and this 2012); the gasser is a lot cheaper than the diesel ever was...it might not tow as good, it might not get exactly the same mileage; but it does everything I need it to do and I won't feel bad trading it in a couple years. And the injectors probably don't cost $600 a piece...if I ever need to replace them.

Prokopchuk_9 · July 29, 2013

No man, you can look anywhere on Craigslist or kijiji or at different dealers across Canada. If you compare the two the diesel is always 6-8k more in price. Almost everytime. Heck mine is 6 years old almost I bet I could still fetch 30k for it even without all the mods!! My 06 sold for 15k LOL, take a look at any fully loaded LBZ Duramax. They are still selling for 25-30 bone stock, even high mileage ones still going for 20-25!!

I'm standing my ground on this one, it might be different down there because the fuel price is so high but here it's always much cheaper for diesel usually. I can go longer between maintenance, get much better fuel economy and ill still fetch at least 25k for It even at 250k Kms.

Injector problems are a thing of the past, yes it does exist but 9/10 it's from owner abuse or getting bad fuel. Tbh it's no different than buying a gasser with AFM issues IMO gas trucks have just as many issues.

I'm not sitting here saying everybody should go out and buy a diesel. I'm just saying that tey do have long term benefits, I agree 100% that most guys the 6 litre is more than enough. But I couldn't stand getting 7-9 mpg towing my boat or trailer any longer. 300-400 Kms to a tank of premium which cost me $140 to fill each time. My truck gets better mileage towing than the 6L did unloaded!! I go an extra 5000kms on oil changes...and...it's over 600hp

sareljr · December 1, 2013

My ext cab 4x4 2500HD with the 6.0l gets about 10.5 mpg, that's both city and highway mixed. It doesn't matter if I drive like a grandma or a teenager trying to show off in front of girls, it's 10.5 mpg. I'd say if you tow a lot get the Duramax, if you're only pulling a camper three times a year, get a 6.0.