GM 6.0 gas V8 vs Duramax 6.6

Hello. My wife and I are sorting out options for a travel trailer & pull vehicle. We believe a 23' Airstream  (6,000 GVWR) or something of the similar length & GVWR would fit our needs. Our intent is to travel 3-4 months/yr and do not wish to be deterred by the Rockies or other obstacles. The vehicle we believe would serve us well would be a 2x2 GMC Sierra 2500 Crew Cab w/ standard bed.  Engine choices are the 6.0L gas or the Duramax diesel. It appears the 6.0L should have the 4.1 rear end vs the 3.73. Please tell me if I am incorrect, but I believe either engine will comfortably do the job. Other than confirmation that the trailer/vehicle is a good combination, can you also give me an idea of the expected fuel MPG of the diesel over the gas engine while towing in an "average" terrain and conditions. There is an added cost for the diesel which may not make sense for what we plan to do.  Thank you for your guidance. The variables in order to go RVing can be a mind boggling.
John and Joy Dibble
Punta Gorda, FL

Either engine in the 2500 should pull that Airstream handily.  If the Rockies and the Far West are in your plans,  normally the diesel would have the edge, but, shoot, that gasser could take a 20-30% HP hit and keep on hauling that 6000 lb GVWR trailer just fine with either the 3.73 or the 4.10.

Thank you Carl. I was hopeful that Joy and I were on the right track with the 2500 Sierra. With regard to 6.0 gas, I guess that since the engine has enough power that either differential will work, am I correct that there should be fuel economies in having the 3.73 rather than the 4.1 or would the engine labor to much? The second question I have deals with the best guess on the MPG under tow with the gas vs the diesel option.
Thanks again for your help.
John and Joy Dibble
Punta Gorda, FL

Sorry you have limited yourselves to a single choice of vehicle.  But be that as it may.  While either motor will pull the intended size of vehicle, the diesel will do it much easier and return much better fuel economy.  Regardless, I would opt for the one ton, 3500 series truck first.  You gain some in GVWR capacity and the cost difference is maybe 200 dollars.  The GM offering diesels only come with the 3.73 rear end ratio as GM believes they know better.  The Allison automatic is a nice transmission and when towing you really need to let it do it's job.
Pulling with the gas motor will probably get you in the neighborhood of 8-10 MPG.  Same load with the D'max should return 12+. and no noticable decrease in performance when in the mountains of the west.

Donn, I appreciate your feed back. Actually, our focus is not limited only to the GMC; it just appeared to us that the truck got good reviews and could accomplish what we would ask of it. I would be very interested in your first choice of trucks knowing the length (23-26 ft), the approx. GVWR and that mountains may be on the horizon. We are new to this stuff and we have read not to undersize the vehicle for many reasons (saftey being #1) which is why we are turning to experienced people for advice. Thank you for your helping us out.
John and Joy Dibble
Punta Gorda, FL

Personally and this is coming from a Chevy Duramax to a Cummins, but personally if you are looking at a new truck?  At least give the new Dodge a look.  They are getting rave reviews from all that I have read about.  After owning both I am really more impressed with the Cummins that I ever was with the Duramax, and I liked it except for the overheating problem in the year I owned.  My Dodge pulling the same load (13,375 pound fiver) will run all day with the cruise control on no matter what it comes up against.  The Duramax just seemed to struggle more with the exact same load.  Looking at any of the new trucks i am still scared of the Urea injection technology that GM and Ford are employing.  I would give that technology at least a year.  Dodge is using the same system it introduced in 2007 and largely seems to have the bugs worked out now.
As for size, like i said i would not ever consider a 2500 (3/4 ton) ever again for serious work.  With a diesel motor there is just not enough room left over for cargo.  Instead get a 1 ton SRW ( single rear wheel) in your choice of cabs and drive configurations.  I think you will be more than pleased with the diesel option.  while the 6.0L GM gas motor is a good motor, it will consume far more fuel towing than a diesel and will struggle more in the mountains or when loaded to near it's capacity.

That 6.0L engine is going to have to rev really high to produce the horsepower needed on any sort of steep grade, East or West. It will get up ok, but it will be noisy. The 6.0L needs nearly 3000 RPMs to produce 200 hp and a whopping 5400 RPMs to produce its 360 HP peak.  Most people would back off long before that, thinking the engine is screaming in agony. It isn't in agony, but it definitely is screaming! The slightly lower power version of the 6.0L (used in some models) is 322 HP at 4600 RPMs.

The 6 cylinder Duramax diesel will deliver its full rated roughly 300 hp (depends on the year)  at  2200 rpm and never whimper. The new high performance V8 Duramax runs all the way up to 397 hp at 3000 rpms, but you won't have to go that high with a 6000  lb trailer.

edit: GM doesn't offer the 6 cylinder Isuzu diesel under the Duramax name, so the sentence above is irrelevant.

I own the 6.0 and pull a little heavier trailer than you are considering (8,000 #'s).  I got the 3.73 rear as I have plenty of extra towing capacity and wanted the better gas mileage.  I get about 10 MPG, depending on how hard I push it.  I usually don't go over 60 MPH and get the 10 MPG.  It tows just fine and from what I hear, the diesel does not get much better mileage.  Maybe 2 MPG.  There is a lot of difference in initial cost, especially if you don't need some of the whistles and bells that are required when you buy the diesel.  You can get a gas engine without all the power options, etc, and proably save about $10,000, if you feel you don't need them.  That said, the diesel will tow a lot more and if you decided to move up quite a bit while you still have the truck you are buying now, the diesel could handle up to about 15,000#.

Both good choices but your initial quesiton dealt wiht whether the 6.0 would tow your rig and it will.  With quite a bit to spare. 

RV Roamer said:

That 6.0L engine is going to have to rev really high to produce the horsepower needed on any sort of steep grade, East or West. It will get up ok, but it will be noisy. The 6.0L needs nearly 3000 RPMs to produce 200 hp and a whopping 5400 RPMs to produce its 360 HP peak.  Most people would back off long before that, thinking the engine is screaming in agony. It isn't in agony, but it definitely is screaming! The slightly lower power version of the 6.0L (used in some models) is 322 HP at 4600 RPMs.

The 6 cylinder Duramax diesel will deliver its full rated roughly 300 hp (depends on the year)  at  2200 rpm and never whimper. The new high performance V8 Duramax runs all the way up to 397 hp at 3000 rpms, but you won't have to go that high with a 6000  lb trailer..

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  The Duramax is only offered as a V8 & the newer ones do have more horsepower & torque plus are quieter.

I was a bit off-base mentioning the 6 cylinder version.  Isuzu makes one, but it doesn't have the Duramax name and Chevrolet/GMC only offers the V8 diesel. Forget I said that!  :-X

Earlier year Duramax V8's have lower horsepower and lower peak RPMs, though. The new version for 2011 is a hot one!

One thing that's been hinted at, but I don't believe clearly spoken about here is what's in your future.

Are you absolutely positive that this will be your last RV? If not, try to think about what you might be looking at for in the future. If it's anything bigger, buying a larger truck now will be cheaper in the long run. Otherwise, you'll be looking for a larger truck next time.

The Airstream's that I've looked at are beautiful, but all feel small nor do they have a lot of storage. Depending on how you pack or length of a trip there might not be enough room.

Another thing to think about regarding diesels. Yes, the initial cost hurts, but diesel trucks have been retaining their value in relation to the gassers. So in the future should you need to sell you should (no guarantees in life) be able to recoup the cost.

I've towed with gas and diesels for years.  For my money, it is diesel all the way.  I love the low rpm torque of the diesel.  Lower rpm equals less fuel use and longer life.

best post so far is the one about what you plan to tow in the future, in the typical male fashion you will eventually upgrade to something bigger like the rest of us do until you get through that craze and you start downsizing or go full blown motorhome and sell the house.
Anyway, our business has 3 chevy 6.0 gas engines and 5 duramaxes, the youngest 2 are 08 models, i'm not a GM guy at all but I do like the D-max, I also like the Cummins and the Powerstroke 6.7 seems to be very impressive with power and fuel mileage.  I do not like the 6.0 gas for towing, it gear hunts like crazy, we have (2) C2500's with a 6.0 and a 3500 dually, they have all had a lot of work done on them, especially the transmissions, you are only towing 6000 now and a 6.0 will tow that like a champ but if you plan on upgrading to a trailer that weighs 10,000lbs+ you're going to regret getting the gasser.  And if you do buy a truck, don't stop at the 2500/F250, the 1 ton SRW is exactly the same, rides the same and all, except it has more capacity.

Good advice, Stewie.  That 6.0L just won't hack a bigger trailer. Ought to be ok with the one he plans now, though.

I've looked at the specs on paper, then towed with each type.  Somehow paper never translates to actual performance.  In my post above, I mentioned the rpm level where the power is made, and I'm of the opinion that this makes all the difference in the world.  When I tow side-by-side with similar loads (we're typically towing built off-road rigs on 2-axle car haulers, plus gear, tools, and camping stuff) the gassers are wound up tight going up hills while I'm backing off the throttle running under 2000 rom.  We both run up the hill at the same time, but one rig is working hard and the other is just a tad over idle.

My tow rig is surely nothing special.  It is a 96 Dodge D2500 w/Cummins 6BT (5.9 6 cyl).  I estimate power output with my slight mods at about 280 hp and 750 torque.  On a round trip from Louisville, KY to Seymour, MS, I averaged 17.9 mpg loaded, running slightly over 70 mph on average.  Mods are, open air filter, #10 fuel plate in stock location, turbo set at 20#, 3000 rpm governor spring kit, and timing set to 16*.  Cost for those mods was under $300.  Truck has no problems at all pulling 8000#, our normal load.  Hardly breaks a sweat, in fact.

On newer models, the factory has bumped power output to similar levels to my truck modified (mine was de-tuned from the factory to 160 hp, 450 torque, as were all the Dodges of early vintage).  I expect to boost power production, and hopefully miles per gallon to about 400 hp, 900 torque, and 20 mpg towing.  Many are doing just that with similar setups.

I <heart> my diesel truck...

Sounds like you should get a Duramax JD. I wasn't clear on wheather you are buying new or used. I might opt for a new Diesel, and a used gas(or gasser as it seems to be called here) ;D I am not 100% sure, but are the maintinence cost higher with diesels? Though if you were getting a new one, or maybe very lightly used with lots of engine warranty left, you woldn't need to worry about those expenses.

diesel ftw!

either truck will do, the duramax is better , for towing. in 2004 I bought brand new Chevy 2500 with the Chevy 4 speed auto crew cab, I put 32,000 thousand mile on that truck 6.0 liter 4.11 gears it ran good, the ave milage from the day I bought it was 9.4 mpg. In July of 07. I bought the same truck but new body style Duramax 3.73 gears. ave mpg 15.1 after 25000 miles. the durmax is way better for towing it pulls harder at a lot less rpm. But It also comes with a price tag ultimately I think the 6.0 is cheaper to operate. where I live in norther ca diesel cost more than gas. and if you buy new the diesel cost $5000 more

I own a 2008 Chevy DuraMax 6.6 diesel 4x4 with the 4 door crew cab.  It is an awesome truck with as much power as you'll ever need.  I just pulled my 27" Hornet Hideout toy hauler from Florida to Illinois.  I had the cruise control set on 70.  I got about 10 MPG.  Diesels 2007 and newer have more emissions controls on them than older diesels and it has hurt their MPG's.  You can (illegally) remove some of the emissions controls and use after-market programmers to improve the engine performance, with a choice between power and economy.  HOWEVER, you'll void your warranty if you do this, so don't do that.  If I hadn't been in such a hurry to get home, I would have just slowed down by 5 to 10 mph and improved my economy that way.  I didn't notice much difference in pulling in tow/haul mode or regular. 

If you are familiar with I-24 between Nashville and Chattanooga, you know about the "mountain" at Monteagle.  My truck pulled my trailer up the mountain and never shifted out of overdrive.  On the way down the other side, in tow haul mode, the DuraMax has built in engine braking.  I can't imagine there is a better truck for towing than the Chevy DuraMax diesel.

IMO, go with the diesel.  The resale will be higher, the engine will last longer and you'll never lack for power.

Shonrt1 said:

IMO, go with the diesel.  you'll never lack for power.

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Do what he said for what ever brand you choose.
J

If you are going to buy a used Diesel, I have to throw my opinion in there.  I am on my 2nd 7.3 liter equipped truck.  Talk about reliability, my first one was a 97 F350 crew cab 4X4 with an 8 foot box, long and heavy truck.  I put an edge evolution programmer on it to boost power and fuel mileage.  towed with it at least 3 days out of the week (usually a 9900lb T300 bobcat on a 3500lb trailer) and she gave me only a couple of minor problems (Cam sensor and vacuum pump), I sold it with 288,000 miles on it and it was running better than when I bought it.  My 2001 F350 is even better, it pulls my 34 foot Fiver (12,500lb GVWR) RV with ease, last trip was to the UP of Michigan (not too mountainous) but got 12 MPG.  The truck has almost 200,000 miles on it and has been trouble free so far.  If you buy the right diesel your maintenance costs are a non issue.  With that said, stay away from the 03-07 Fords with the 6.0 diesel, I have one of those too, head gaskets, injectors, bed plates, EGR (cooler and valve) and the tow bills.