Ok, I have a Dodge 1500 Quad cab with the 5.7 hemi.

I also have a Dodge D350 (3500 series) with the 5.9 Turbo diesel,

The hemi has 345 horsepower with 375 lbs of torque,

The diesel has 160 horsepower with 400 lbs of torque.

Both are pretty close to evenly matched. Of course Torque is the factor.

Both trucks pull 8,000 lbs pretty much the same, The hemi getting around 14 mpg loaded, the diesel around 17 mpg. Empty the hemi gets 22 to 27 mpg and the diesel gets around 22 to 27. (almost perfect conditions mind you,)

As far as maintenance, The hemi requires the spark plugs to be replaced every 40,000 miles, (no cap,rotor etc,) Ignition wires around 75,000 miles, Oil changes every 7500 miles along with fuel filter change every 10,000 miles.

Oil capacity is 8 quarts, incl. filter

The diesel needs oil changed every 5,000 miles, along with dual fuel filter and water seperator.   Oil capacity is  16 quarts incl. filter.  An injector failure on a hemi is $116. ea.  On the diesel and injector is around $400.  A fuel pump on a hemi is $134.  and a fuel pump on a diesel is around $419. (turbo's on a diesel can run from $800 to $2200).

Depending on your financial arrangement, Diesels are nice, BUT, are a bit more expensive as far as maintenance and repairs, The diesel is made to pull heavy compared to a gasser.

Im NOT endorsing Dodge, but I have run Fords and Chevy's,, Ford makes an almost bulletproof 7.3 diesel compared to Dodges 5.9 Cummings workhorse.

Chevy diesels are somewhat OK, But still have a few bugs to work out as far as injector and engine heads getting overheated. A good rule of thumb is its better to have a little more power then you need , then to be underpowered when needed most. F.Y.I.  A ford powerstroke 7.3 is expected to have injectors replaced at 100K,, so if your planning on buying a used diesel, ask if the injectors have recently been replaced and if not, expect a chunk of change to have them replaced.  Hope this helps a little bit when deciding a gasser verse diesel.

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Tags: Dodge and Ford Diesel Trucks for RVing, RV hauler gas or diesel, diesel trucks, gas versus diesel


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Comment by Lakota Wolf on July 7, 2014 at 1:03pm

Unless my 2 Calculators are broken, or my basic math is off, (I graduated 3rd grade 4 times).

With a fuel tank empty, adding 8 gallons of fuel, (5 gallon, and 3 1 gallon jugs). and (carrying 10 extra gallons just to be safe). I drove the full 200 miles, (193 miles on the straight).Ran it down till fuel level buzzer went off. (leaving about half to 3/4's of a gallon floating in the tank)

Basic math,, 8 gallons @ 200 miles, equates to 25 mpg.(I took into concideration the fuel left in bottom of fuel tank).

(the fuel tank is a drop down spout and you can look down into the fuel tank).

The only difference on the trans is,its a Dayton 4 speed automatic. with 5.83 rear gear.12 bolt plate.

Comment by John Demarrais on July 7, 2014 at 5:40am

Driving habits don't affect fuel mileage THAT much.  I drove my 1985 Ford F250 with an IDI, naturally aspirated 6.9 diesel for 400 miles around the Michigan UP.  45 MPH all the way on flat roads, no wind and 1000 foot average altitude. Got 13 MPG for the trip.   When driving it at 75 MPH it got 11 MPG. Note both figures with an empty single rear wheeled truck.   4WD, extended cab, C6 trans and 4.10 axles.

 I did exactly the same with my 1992 Dodge 4WD, extended cab, Cummins DI 5.9 intercooled/turbo, 5 speed manual OD, and 3.50 axles. Got 21.5 MPG.  Did it again with a pop-up roof slide-on camper and got 18.5 MPG.   Later - took the same truck to Kentucky and often drove 70 MPH. Still with the camper on the back. Got 17 MPG for the trip.

 Took the same Michigan UP trip with my 1994 Ford F250 with extended cab, 4WD, 7.3 turbo IDI, E40D (overdrive lockup auto), and 4.10 axles.  45 MPH the whole way. got 17.5 MPG for the trip. Did the same later with a high-roof slide-on camper and got 14.5 MPG.

 I drove a new 1995 Dodge with a 5.9  Cummins with 4WD and five-speed OD, 3.50 axles down to Long Island and back to central NY. 60-65 MPH, Light winds.  1600 foot elevation to 100 foot elevation. Got 20.5 MPG.

 Note that most of these figures are with the old diesel that had better fuel mileage potential then the new diesel that has less energy per gallon.  Anyone giving figures of high 20s in a full size pickup are citing figures that beat the new Dodge Ecodiesel that has an engine half the size. Hard to believe and/or account for. I know I've been fooling with diesels for 50 years. Haven't seen a full truck yet make high 20s unless it had a small engine.  Like a Cummins 3.9 4BT that got 26 MPG in one trip when installed in a Ford F150 2WD.  I'll also note that back in 2010 - several companies did side-by-side road tests of the new Chevy, Dodge, and Ford trucks.  Tested them empty, pulling trailers, etc. Dodge took last place and the dually they tested empty at 65 MPH got 14.5 MPG.  Maybe you guys have some magic fuel or something out there. I've never seen it.   

Comment by Lakota Wolf on July 6, 2014 at 9:47pm

I must be TO easy or just TO safe cautious. I prefer to drive 55 maybe 60 tops. I have seen way to many travel trailers scream by me on the interstates at 70 and up, blow a tire, and see them sitting on the side of the road with damaged side skirts, and even a few sitting on there side.

I may be slow, But I'm only usually a couple minutes behind the ones who need to get there yesterday.  Maybe thats a contributing factor to my fuel mileage. Not sure.

Comment by Lakota Wolf on July 6, 2014 at 11:58am

Was holding steady at 25.to 26... I know  a couple mpg's don't sound like much till you add it up in miles and cost. Another factor is when Im cruising I stay at the 55 to 60 mph range,(even though speed limit is 65 to 70 here). I stay in the right lane and watch people scream by at 75 to 90, (which I assume they are in a hurry to get somewhere).

Comment by John Demarrais on July 6, 2014 at 7:09am

The new long-range fuel mileage tests are in for the new Dodge Ecodiesel in a 1500 truck. I read four different test reports and all were near the same. 


2014 Ram 1500 Ecodiesel with 3 liter V6.  $53,000.  Best fuel mileage at a steady 65 MPH– 25.3 MPG.  Worst fuel mileage (on highway) -  21.4 MPG.

So you guys who report in the high 20s with old trucks have figures greatly surpassing the latest tech. 

Comment by John Demarrais on July 6, 2014 at 6:44am

Question for Lakota-Wolf.  You say fuel mileage "dropped" to 24 MPG on your 1992? What was it before?   I've never experienced high figures like this with any diesel pickup on the road with mechanical injection.   I was working as a diesel mechanic when Dodge came out with its first diesel pickup in 1978 (a big flop).  When the Cummins came out - it was a big deal. I kept track of many in my area of NY.  Also became a member of the turbo-diesel register where 100s of owners posted their fuel usage figures. I've yet to encounter a Dodge truck with any 5.9 to get over 23 MPG.  20 MPG was pretty much the norm for most when driven empty @ 65 MPH.  Getting 20 MPG was a big deal considering that the Ford 6.9s and 7.3s were lucky to get 17-18 MPG.  I will note that when my 1992 was new - the truck gave 22 MPG if fuel mileage was calculated with the odometer in the truck.  I found out years later that the odometer lied.  Dodge had the wrong speedometer gear-box on the transfercase that gave false readings. Once I installed the correct one - fuel mileage read as 20 MPG on a best day.  That's a steady cruise @ 65 MPH with no winds, no load, no jack-rabbit starts, and no higher then 1200 feet above sea level.  This in a 4WD extended cab truck. A lower and shorter 2WD can do a little better. 

Comment by Lakota Wolf on July 5, 2014 at 12:05pm

My 92, Dodge diesel, (ole Red), just made a trip, (200 miles) and mileage dropped to 24 mpg on the straight. Its concidered 1st generation turbo, 12 V. Its also a dually and not 4x4.

I think I'm doin pretty good,and the curb weight is 8.770 lbs, not counting the 400 plus lbs of mics gear stowed in the sleeper unit. I can attest, that I don't do jack rabbitt starts and just accellerate gradually and build speed up to a nice cruising speed. Ive seen people floor it just to go from zero to 50 in what they hope is a 4 second drag race to the next light. I think my fuel mileage mostly has to do with how I drive, slow,steady, But not like grandma on a sunday drive.

Comment by John Demarrais on July 5, 2014 at 7:45am

Can't say my Dodge-Cummins ever got better then 20 MPG on a slow flat highway run when empty.  27 MPG sounds incredibly high.  Mine is a 92 - 4WD, extended cab, turbo/intercooled 5.9, 3.50 axle ratios and Getrag five speed manual trans.  I also have a 1982 K10 Chevy with a 6.2 diesel, 3.07 axle ratios and a four speed manual with OD. 23 MPG is the absolute best it ever got.  Also have a 1994 Ford F250 extended cab, 4WD, with a 7.3 turbo IDI (NOT Powerstroke).  Gets 17 MPG a its best with the E40D trans and 4.10 axles.  The only diesel truck I own that has ever gotten 27 MPG is my 1985 Isuzu PUP 4WD with a 2.2 liter diesel.

Diesels are much more expensive to repair unless a person does all their own work.  A rotary mechanical fuel injection pump can run $1000 to replace. Thus good reason to put lube additive in highway diesel.  Injectors?  I recently put new nozzles in my 94 Ford and it cost me $7 each. Not much more then spark plugs.   I also put new injectors in my Chevy and they were $5 each.   My Dodge/Cummins 5.9 had 220,000 miles and I've never pulled the injectors out to check yet. Runs like new. I DID have to fix the automatic timing advance on the injection pump once.

In regard to engine durabilty?  The International Harvester 7.3s that Ford used started out as big HD gas engines in school buses.  They have been tested to last every bit as long as a 5.9 Cummins although the 5.9 is certainly built heavier.

With diesel fuel now often 50 cents more per gallon the regular gas  - the advantages of owning a diesel are dwindling - at least for me.

Comment by Lakota Wolf on March 3, 2014 at 10:03pm

I havent come across a 502 in a long time. Those my friend are Work horses. The Government used alot of those in there mid range 1 ton service trucks. And you getting 8.5 mpg's your doing awesome concidering almost 16 K in weight. I can remember they had some serious torque and purred like a sewing machine at highway speeds,, they have a good upper power band that just makes the engine hum.

Comment by Buford T. Puser on March 3, 2014 at 9:29pm

We love the carbureted 502 HT Chevy crate engine with 500-foot-pounds of torque in our 1984 Windcruiser.  Motorhome. It weighs 12,800 pounds with 80 gallons of gas, two people, luggage and one small Jack Russell Terrier.  Pulling a 3,500-pound trailer at 57 mph with the generator powering two roof ACs, we consistently get 8.5 mpg or better.  The 3-speed 400 Turbo never even drops into 2nd up long freeway hills.  It holds 57 mph and leaves semis in the dust.  We use Amsoil in the crankcase, transmission and differential.



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