Fuel Mileage with Ram 2500 6.4 HEMI HD vs Cummings Diesel

[Kirk W]

Since the original poster hasn't been back since Dec. 2, it don't seem to be hijacking to join in the discussion. I have owned 3 diesel vehicles over the years and had good results from them all. My first was a 1984 Ford, Tempo sedan and it was the most fuel efficient car I have ever owned. Shortly after that I got a used, 1979 Datsun diesel pickup that had an aftermarket turbo added to the 4 cylinder diesel engine. But I didn't tow with either of those two. Today I own a 2003 Dodge 2500, Cummins powered truck and tow our travel trailer with it. Bought the Dodge in 2014 with 98k miles and while it is by far the best towing vehicle that I've owned, it also costs the most to maintain. 

My son is towing a 27' travel trailer with a 2022 Ford, F350 7.3L gas engine. His first long trip he got 9.5 mpg when towing.

 

Edited January 2, 2022 by Kirk W
Add a little more.

[whj469]

If you are buying a truck? A 250/2500 is not what you should have to tow a 15,000 # trailer. The pin weight will overload the truck. 250/2500 don't have the weight rating to tow a 15,000 # fiver. I wouldn't buy a gas engine. Diesel is the way to go. Yes, it will be a lot more. I tow a 16,000 # fifth wheel with a 2019 F350, Crew Cab, long bed, 4X4, diesel, SRW and that does the job well. My 2011 F250 didn't do so well and it was overloaded.

[rynosback]

The capability of the truck should be the first concern. Always better to have more truck as it make towing easy and not white knuckled. Safety trumps fuel mileage in my book. What about cost of repair and down time for repairs towing towing with something at its max? 

[tiehand9]

I purchased my 21 RAM 2500 Hemi 15 months ago and have put almost 50k on it. 60-70% of those miles with 14-15k loaded 5er behind it. It’s all about expectations.  If I use cruise control when towing my MPG is down around 7.5-8.5 @ 62-65 mph. If I stay away from cruise (or limit use to flats) I can get 9.5-10.5 mpg at 65-68 mph while letting speed taper off on inclines which the cruise won’t allow.  Up real hills I can still go any speed I want if I don’t mind seeing mpg drop to 2-3. I choose to keep rpm below 3500 and let speed drop to 40ish. I don’t use “tow mode” and I generally drive at speed that the tranny can hold 8th gear. I can hold 8th down to 50-55 mph before a downshift if I’m careful. My trans runs at 168 degrees on flats and heats up to around 175 on hills, which is well below temps to be concerned about. I don’t keep up with the diesels going up hill if I want to maintain reasonable mpg. I do generally pass semis on hills if the left lane is clear.  With no load on the highway I get 18-21 mpg @ 75 mph. Again, it’s all about expectations.  With my 2500 Hemi I have enough cargo capacity for my 5er.  With a diesel I’d need a 3500 due to the drop in rated cargo capacity.  I’m fine with slowing down up hills and I don’t ever feel like I need to rush.  In fact, most trailer tires on RVs in this weight class are only rated for 65 mph anyway. And just before anyone claims I’m overweight, my 21 Hemi 2500 4x4 crew with 4.10 gears is rated to tow 16800 and 3100 cargo.  I weigh all the time and adjust to stay below rated capacity. I did once find the rear axle of my truck over by about 300 pounds and immediately adjusted cargo to correct it.  I’ve considered a swap to a 2016-2017 diesel 3500 (similar value) so that I’m not so close to the limit, but there’s more to it than just higher capacity and I’m comfortable with my under $100 oil changes and lower price fuel.  The one thing I’d like when my 40’ 5er is attached is to be able to use the semi pumps instead of searching and maneuvering for the gas pumps.  In fairness to all I’ve never driven a diesel with a load behind.  Maybe once I do I’ll change my tune.  

[rbertalotto]

On 1/2/2022 at 2:07 PM, whj469 said:

If you are buying a truck? A 250/2500 is not what you should have to tow a 15,000 # trailer. The pin weight will overload the truck. 250/2500 don't have the weight rating to tow a 15,000 # fiver. I wouldn't buy a gas engine. Diesel is the way to go. Yes, it will be a lot more. I tow a 16,000 # fifth wheel with a 2019 F350, Crew Cab, long bed, 4X4, diesel, SRW and that does the job well. My 2011 F250 didn't do so well and it was overloaded.

Just a data point. The 2500/6.4 gas will have roughly 1000 pounds more payload than the diesel. There is a huge payload penalty with the diesel. I'm not talking "tow rating".... that's a different story.

[rbertalotto]

Great video from a diesel mechanic on this subject....

 

[Vegas Teacher]

Have you ever thought about getting an HDT? Go over to the HDT part of this and look at us on the class 7/8 part of the escapes site, you might be surprised.

[Ray,IN]

On 12/2/2021 at 8:09 AM, Jinx & Wayne said:

You don't mention a year or model, but gas or diesel, a 2500 is probably not enough truck for a 15k fiver.  Payload and axle capacities are probably too low.

Wayne & Jinx
2017 F-350 diesel, dually
2006 Carriage Carri-Lite 36KSQ

I totally agree; been there done that. a 3/4T is not enough truck for a 15,500# 5er. The Cummins diesel worked great, but the weight of the 5er pushed the truck around all the time. Traded for a 1T dually and towing became easy and comfortable again.

[ddm502001]

Finally got license on my HDT Toter, it is overkill on overkill as to size but was a trade deal that could not pass up.  Took a farm trailer(Mine is Weight Tagged) with a old Ford F250 longbed to OK for a sale where it sold better than up here plus hauled a load of obsoleted planter equipment to the guy got the truck from.  A Pin Hitched Goose with roughly 8700# materials on it at 75mph average on cruise most of the time got 8.8mpg.  Same guy that hauled this up from OK with a F550 managed 9.2 on a 6.7 diesel at 70mph so can get better but still close.  My KW weighs 19500 at half tank fuel.

His oil changes are at 5000miles due to severe duty type, the KW/Cat will be roughly at 20,000 miles as typical for these or annually, his has 14qt oil Cat uses 32qt oil same weight oil, one filter each engine but Cat is four times cost of his.  When averaged out the Cat is more cost effective just higher each service cost.  Tires on mine will make 100,000mi or four years, whichever comes first, his may make 45,000 and be worn too far.  Brakes(Drum) I may not ever have to replace, his(4 wheel disc) are estimated at 14-18 mo service life towing.

 

Weighing apples to apples I have the better longevity choice overall.

Dave

Edited January 22, 2023 by ddm502001
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