Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > TRAVEL TRAILER, 5th WHEEL & TRUCK CAMPER FORUMS > 5th Wheel Discussion
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 09-16-2015, 12:38 PM   #1
Junior Member
Join Date: Sep 2015
Posts: 24
5.9L verses 6.7L inquiry

5.9L verses 6.7L inquiry...which is the better engine???
I am looking to buy a Ram 3500 Dually...... The tow limits are close on each....There are just so many more of the 5.9L to choose from than the 6.7L.... Which is the better engine... I know the gear ratio has alot to do with the towing... however, it seems there are more of the 3.73:1 than there are the 4.10:1...... will i be ok with the 5.9L/3.73:1 as long as i am within or close to being within the limits.....
SteveFortune is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free! RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 09-16-2015, 01:04 PM   #2
Senior Member
Dasmoeturhead's Avatar
Join Date: Jul 2014
Location: Planet Earth
Posts: 1,059
There both good diesel engines, and both of those gear ratios are good towing gears. That being said , the 6.7 is a towing beast completely stock. No need to chip it or whatever for more power. Now the 5.9's are wonderful engines, but if your going to tow a big 5er your probably going to want more power. The 5.9 will do the job just fine, and will pull any hill, but the 6.7's don't need any mods.

The 5.9's are simpler to work on, and there's no limit to how much horsepower you can build one of these up.

Now I'm sure you'll get a lot of other opinions on this matter.
2022 Grand Design 150 series 260RB
2021 RAM 2500 Laramie CTD 4x4, 68rfe. 3.73
Dasmoeturhead is offline   Reply With Quote
Old 09-16-2015, 01:47 PM   #3
Senior Member
powderman's Avatar
Join Date: Mar 2010
Location: N. E. Ohio & Lady Lake Fl.
Posts: 1,120
The most likely reason you see more 5.9s is they have been around much longer. I have the 5.9 with 4:10 gears and if I had a choice I would go with the 3:73 unless you plan on doing a LOT of heavy mountain pulling. My friend has same truck as mine but with 3:73 and typically gets 2 plus more mpg. No major problems that I can see on either engine. I love mine and it did a great job pulling my fiver up a 13% grade recently.
powderman is offline   Reply With Quote
Old 09-16-2015, 08:08 PM   #4
Registered User
Join Date: Aug 2014
Posts: 1,346
Buy a new 15 off the lot, there are great discounts out there be sure to get an Aisin trans. More power and lower starting gears get the load moving easily. They are towing machines.

The 5.9 is a great engine but has a 4 speed trans. 6 speeds makes a world of difference when towing!

Rear air ride is great also. 4:10's will get the most towing capacity. I am extremely happy with my 4:10's and Aisin/6.7 combo.

The oil contamination is not a big deal any longer with the 13 and newer 6.7's the oil change interval is up to 15K now and the oil actually stays clean for a long tome compared to my 11 HO 6.7.

Truck and RV combined 32,540#

15,040 sitting on the 6 truck tires. Can't come close to that with a 5.9 Dually.

Cummins12V98 is offline   Reply With Quote
Old 09-18-2015, 06:33 PM   #5
Junior Member
Join Date: May 2008
Posts: 10
Love my 15 a towing machine and I came from 2007 Duramax
ddown is offline   Reply With Quote
Old 09-19-2015, 08:19 AM   #6
Registered User
Join Date: Aug 2014
Posts: 1,346
Originally Posted by ddown View Post
Love my 15 a towing machine and I came from 2007 Duramax
Fill in your profile, helps with answering questions.
Cummins12V98 is offline   Reply With Quote
Old 09-19-2015, 08:32 PM   #7
Rickthescot's Avatar
Join Date: Sep 2013
Location: Richmond, TX
Posts: 39
My 6.7 is so quiet compared to the 5.9 I had. Many people while riding with me ask "Is this a diesel?". It also tows like a champ.
2008 Carriage Domani , 2010 CTD 2500 short bed, Fabex Sidewinder, Husky 16KW
Rickthescot is offline   Reply With Quote
Old 09-21-2015, 09:55 PM   #8
Join Date: Aug 2013
Posts: 63
The 5.9L is certainly dependable as its been around awhile. The 6.7L has been increasing in power each year since its debut in 2007. When I bought my 2007 I had the choice of a new 5.9L or the 6.7L. I opted for the 6.7L for 2 reasons. The 6.7L has a far better designed 6spd transmission while the 5.9L's tranny often is the weak link in the drive train. 2nd reason is the 6.7L's turbo includes a built in exhaust brake. Really makes towing down steep grades easy.

That said the 2007/8 6.7L had a ton of growing pains. The emissions system on them were very problematic with numerous TSB's to correct. My turbo was replaced 3 times, EGR and heater grid cleaned repeatedly, O2 sensors replaced etc. I firmly believe the problems were all figured out and resolved. All issues warranted. Last issue was 4 years ago at around 30,000 miles. I now have 95,000 miles and zero troubles since.
mileshuff is offline   Reply With Quote
Old 09-21-2015, 10:26 PM   #9
gebills's Avatar
Join Date: Oct 2014
Location: Florence AZ
Posts: 37
5.9 versus 6.7

Originally Posted by Rickthescot View Post
My 6.7 is so quiet compared to the 5.9 I had. Many people while riding with me ask "Is this a diesel?". It also tows like a champ.
Referencing noise, I think my 6.7's have been a slight bit more noisy than my friends 2015 Ford, but I've been so happy with the towing ability and the trustworthiness of the 6.7's, that I have no reason to look elsewhere. My "Ford friend" had to move my 5'er about 40 miles last week (due to a broken leg on my part) with my Ram, and he commented that it felt like a smooth pulling and shifting rig. My wife and I both enjoy the low noise level from the 2010, the 2011 and the 2015 that we've had. Our reason for trading so often is that we couldn't seem to get the selection right. 3rd time was a charm with the new dually.

The mileage on the 5.9 would likely be several MPG better under normal driving conditions, unless your towing in wind. I think you would find, as I have, the 6.7 mileage doesn't vary too much, wind or not. Mechanically, we have had "zero" mechanical issues with the 3 trucks. The one we currently have is towing in the 30K lb. GCVW range. With the 6 speeds and Aisin tranny, it pulls like a champ with the 3.73 gears.
2018 Thor Synergy pulling a Fiat Toad via a Demco tow bar.
gebills is offline   Reply With Quote
Old 09-25-2015, 05:02 AM   #10
Senior Member
chertz's Avatar
Join Date: Sep 2012
Posts: 542
I am alittle biased, but I choose a 5.9L for two reasons... first was cost... a new truck was not reasonable for me. Second was emissions... the early 6.7's prior to DPF scared me. Too many friends spending small fortunes either fixing or replacing those emission systems. Although the 6 speed auto and exhaust brake would sure be nice. All in I absolutely love my 5.9L.
2014 Ram 3500 CCLB 4x4 Dually 68RFE, 370/800 Cummins 3.42 highway gear - Deep Cherry Red
2016 Coachmen Chapparal 360IBL
Sold - 2005 Dodge Ram 2500 SLT QCLB 4x4 - Cummins Power
chertz is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
New to us mechanical 5.9L. What do I need to know? Fugitive861 Cummins Engines 26 09-20-2015 10:11 AM
5.9L verses 6.7L inquiry SteveFortune Cummins Engines 5 09-17-2015 04:54 PM
Cummins ISB 260hp 5.9L with a toad dmastroluca Toads and Motorhome Related Towing 9 07-15-2015 11:13 AM
2011-2014 Ford 6.7L Diesel Custom Tuning Available NOW ! 5 Star Vendor Spotlight (Deals, Announcements & More) 0 09-23-2014 06:38 PM
5.9l Cummins / Allison 6spd...Best method for mountains Bad Bolt Allison Transmission Forum 3 10-22-2013 10:49 AM

» Featured Campgrounds

Reviews provided by

All times are GMT -6. The time now is 02:21 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2023, vBulletin Solutions, Inc.