Struggling to decide on gas vs diesel for a 14k 37' 5er

namtaru · July 24, 2023

We are looking to get into a fifth wheel from our current travel trailer, and thus upgrading from a 1/2ton to an HD. I plan on keeping this truck for the next 10 years or so, and am really struggling on going with gas or diesel. The fifth wheel we are looking to get is 14000lbs GVWR and just over 37 feet, and a 2400lb loaded pin weight. We plan on taking it cross country annually with another 8-10 trips in the 60-400 mile range (round trip) locally every year.

Now for the fun part. I work from home, so besides pulling the camper, the rest of my duties consist of going to the grocery store, home depot, and running the kids to soccer. I only put about 8-10k miles a year on my current truck (only about 20% of that is while towing the trailer) but that will go up a bit with some of the longer trips we are starting to plan. On the flip side, I do live in a somewhat rural area, so me hopping on the highway for a 30+ minute drive one way is at least a weekly occasion. I've read every thread and watched every video I can find, but I swear almost all of them are people towing 7k-11k lbs, so it's been difficult finding feedback from people pulling a larger fifth wheel with the gasser (besides JB Reviews, which quite honestly I don't feel like a 20 mile review on a brand new truck really gives me the type of feedback I'm looking for)

I feel like I'm torn between possibly having issues with emissions, or towing at almost max capacity with the gasser. Any feedback from owners would be appreciated. Thanks!

edit: To clarify, I'm looking at a 2024 3500 SLT

Edited July 24, 2023 by namtaru

Steve Hougham · July 24, 2023

8 minutes ago, namtaru said:

We are looking to get into a fifth wheel from our current travel trailer, and thus upgrading from a 1/2ton to an HD. I plan on keeping this truck for the next 10 years or so, and am really struggling on going with gas or diesel. The fifth wheel we are looking to get is 14000lbs GVWR and just over 37 feet, and a 2400lb loaded pin weight. We plan on taking it cross country annually with another 8-10 trips in the 60-400 mile range (round trip) locally every year.

Now for the fun part. I work from home, so besides pulling the camper, the rest of my duties consist of going to the grocery store, home depot, and running the kids to soccer. I put about 8-10k miles a year on my current truck, but that will go up a bit with some of the longer trips we are starting to plan. On the flip side, I do live in a somewhat rural area, so me hopping on the highway for a 30+ minute drive one way is at least a weekly occasion. I've read every thread and watched every video I can find, but I swear almost all of them are people towing 7k-11k lbs, so it's been difficult finding feedback from people pulling a larger fifth wheel with the gasser (besides JB Reviews, which quite honestly I don't feel like a 20 mile review on a brand new truck really gives me the type of feedback I'm looking for)

I feel like I'm torn between possibly having issues with emissions, or towing at almost max capacity with the gasser. Any feedback from owners would be appreciated. Thanks!

I have a 2020 2500 Diesel and a 5er that's 33ft. and loaded it's right at 12k. I get fuel at the trucker pumps because I don't even want to think about trying to maneuver in and around the pumps out front with everybody else in your way. Trucker pumps makes it so convenient but has only diesel and DEF. No unleaded gas. I'm getting ready to order a 2024 3500HD Diesel. Just a thought.

namtaru · July 24, 2023

38 minutes ago, Steve Hougham said:

I get fuel at the trucker pumps because I don't even want to think about trying to maneuver in and around the pumps out front with everybody else in your way. Trucker pumps makes it so convenient but has only diesel and DEF.

I'd be lying if I said I haven't thought about how nice this would be. Currently, towing our 31' TT whenever we take a trip longer than about 160 miles I have to google map possible gas station stops to make sure I can fit in.

UWSkier · July 24, 2023

6 minutes ago, namtaru said:

I'd be lying if I said I haven't thought about how nice this would be. Currently, towing our 31' TT whenever we take a trip longer than about 160 miles I have to google map possible gas station stops to make sure I can fit in.

Get the Pilot Flying J app and look for RV friendly stations. These have RV lanes with diesel and gasoline. I just used it on my 2000 mile tow from Arizona to WI and it was great.

On the truck, after towing for 2000 miles with my gasser and a travel trailer about your size, I'd go diesel for anything with a higher wind profile than a TT. Gasser and Allison will have no problem getting that load moving, but it'll run in 6th or 7th gear in headwinds.

wesd · July 24, 2023

I wouldn't even consider gas for this mission profile. Not for one second.

In general, having had gas and diesel HD trucks, I wouldn't consider a gasser HD because in regular times the resale is terrible.

Especially towing a 5th wheel, do you want to stop and get 30 gallons of gas every 200-250 miles?

My 2500HD Duramax gets 11.5 MPG towing, down from 13 MPG since I went with bigger AT tires. I was lucky to get 7-8MPG when towing the same trailer (30' bumper pull) with my gas HD (2017 F250 6.2). I had to stop about every 3 hours, where now I can stop every 5 hours. Makes a big difference when traveling long distances. Never mind the constant shifting of the gas engine to stay in the power band.

Brummie99 · July 25, 2023

1 hour ago, wesd said:

I wouldn't even consider gas for this mission profile. Not for one second.

In general, having had gas and diesel HD trucks, I wouldn't consider a gasser HD because in regular times the resale is terrible.

Especially towing a 5th wheel, do you want to stop and get 30 gallons of gas every 200-250 miles?

My 2500HD Duramax gets 11.5 MPG towing, down from 13 MPG since I went with bigger AT tires. I was lucky to get 7-8MPG when towing the same trailer (30' bumper pull) with my gas HD (2017 F250 6.2). I had to stop about every 3 hours, where now I can stop every 5 hours. Makes a big difference when traveling long distances. Never mind the constant shifting of the gas engine to stay in the power band.

I concur with this assessment.

I had a 40ft 10,000lb TT that I pulled with a 2016 Sierra 2500 with the 6.0 gas motor. Towing (in Florida), I was getting 6mpg. When we upgraded to a 14klb 5er, I knew I wanted a diesel.

I now have a 3500 Duramax dually and couldn't be happier. The towing experience is night and day.

Have only done 1 significant trip so far but was getting 11mpg and a much more relaxed driving experience. The fuel level anxiety with the gas is significant.

memilanuk · July 25, 2023

Not entirely apples to apples, but...

We've done several (5) trips over the last 6 years from WA state to Bismarck ND, about half with a loop down into western NE - so 2200-3000+ mi per trip. First with an F250 CCSB 6.2L gasser and 30ft TT, the last few with a F350 SCLB SRW 6.2L gasser & heavy TC, both trucks with the 6 spd and 4.30 rear end. Only reason we're looking at a DRW now is because frankly, that TC puts us well over both the GVWR and the rear GAWR. We generally set our cruise at whatever the truck speed limit is, and the gassers go up and over the mountain passes about as fast as I'm comfortable with handling.

The fuel anxiety thing is easily handled with some route planning on something like rvtripwizard.com. We find that stopping every ~3 hrs is just about right for time to stretch the legs, hit the bathroom, etc.

YMMV.

NaturallyAspirated · July 25, 2023

I currently have a gasser and love it. But for you it’s gotta be diesel. Just so happens that I drove a friends 2023 Diesel 3500 tonight and it reminded me of the difference.

In a rural area, the real question is Single or DRW. Seriously.

Edited July 25, 2023 by NaturallyAspirated

64BAwagon · July 25, 2023

In a perfect world where diesel wasnt more expensive than gas, DEF didnt exist and light duty diesels were reliable and didnt cost 10k more than a gasser I would have another diesel. But thats not the world we live in. I tow a 36ft 12K fifth wheel with my 2nd 3500HD SRW crew cab gasser. There are some trade offs for sure but nothing that isnt manageable and with the 10spd in the new 2024 I bought it should make it even more capable.

You for sure have to drive the gasser different. the diesel has the luxury of setting the cruise and letting it go. the gasser requires a little more input. The current 6.6 gasser is close to the HP and torque numbers of the original LB7 Duramax.

Honestly my LLY 2005 Dmax didnt get that great of mileage and the gasser isnt much worse, in fact when calculated at a cost per mile its virtually a wash and thats not factoring for DEF.

If youre budget will take it and you opt for the diesel for the 10yr timeline I would buy the extended protection plan. With the complexity of the diesels and the catastrophic cost of a breakdown (I still think they use customers as Beta testers) I wouldnt own one out of warranty.

I have driven a lot of trucks in my day, everything from an S10 to an 80k, 100ft aerial and worked on every one of them, yet I still drive a gasser.

Just my 2 cents.

Edited July 31, 2023 by 64BAwagon

Ray Pickle · July 25, 2023

6 hours ago, 64BAwagon said:

In a perfect world where diesel wasnt more expensive than gas, DEF didnt exist and light duty diesels were reliable and didnt cost 10k more than a gasser I would have another diesel. But thats not the world we live in. I tow a 36ft 12K fifth wheel with my 2nd 3500HD SRW crew cab gasser. There are some trade offs for sure but nothing that isnt manageable and with the 10spd in the new 2024 I bought it should make it even more capable.

You for sure have to drive the gasser different. the diesel has the luxury of setting the cruise and letting it go. the gasser requires a little more input. The current 6.6 gasser is close to the HP and torque numbers of the original LB7 Duramax.

Honestly my LLY 2005 Dmax didnt get that great of mileage and the gasser isnt much worse, in fact when calculated at a cost per mile its virtually a wash and thats not factoring for DEF.

If youre budget will take it and you opt for the diesel for the 10yr timeline I would buy the extended protection plan. With the complexity of the diesels and the catastrophic cost of a breakdown (I still think they use customers as Beta testers) I wouldnt own one out of warranty.

I have driven a lot of trucks in my day, everything from an S10 to an 80k aerial and worked on every one of them, yet I still drive a gasser.

Just my 2 cents.

Agree with your thoughts. The key is what your doing with your truck the MAJORITY of the time and that is commutes around town and as a daily driver. The gasser will be superior in that role when you consider all cost factors. The only time your gonna wish for the diesel is on your annual trip out west. Is that annual trip gonna decide your choice? Some are speaking of their negative experience with gassers yet they are dated or not apples to apples. I can tell you from personal experience having towed a 12k fiver over 25k miles with a 20' 2500 6.6 it will get the job done adequately on any terrain and is more than enough on most terrain. I have made 2 trips west each over 4500 miles and averaged 8.3 ish on 1 trip and high 8s on the other. In the midwest I typically come in at 9 or alightly over. Your weight is gonna make it a little more challenging but well within the trucks capability. I have no issues getting fuel, does it sometimes require planning? Yes, but its far from a dealbreaker. No knock on a diesel, if where fulltiming it would be my choice as well.

Another JR · July 26, 2023

21 hours ago, NaturallyAspirated said:

I currently have a gasser and love it. But for you it’s gotta be diesel. Just so happens that I drove a friends 2023 Diesel 3500 tonight and it reminded me of the difference.

In a rural area, the real question is Single or DRW. Seriously.

This is the correct answer in my opinion. I have a 2021 gas 3500, and also love mine for my use, but no way would I buy the gas truck for that load and usage.

Edited July 26, 2023 by Another JR

Tater86 · July 26, 2023

Go check out the review from Automotive Inquires on YouTube. He just did a 347 mile round trip with his 5th wheel around Colorado and gives his opinions. I think he averaged 9.3 miles to gallon.

Elite130 · July 26, 2023

namtaru - The following questions are what I asked myself when debating gas vs diesel.

1) Size and weight of trailer.

2) Where do you live?

3) Where do you plan on towing the trailer?

I ask these three questions immediately because the responses, in my experience, help make the decision pretty quick and easy. The first question is obvious... size and weight has everything to do with towing characteristics and how much power it will take to move. The next two questions are related to where you live and where you plan to pull your trailer. Elevation is everything when it comes to ICE engines. For example, I live in Denver, CO at 5,280ft above sea level. When I take a trip, whether it is west along I-70 through the Rocky Mountains, down 2-lane highways, or east along the plains, I will see elevations between 3,500ft in the plains and 11,200ft+ over some mountain passes. Air density and engine performance is very different at those elevations. The mountain passes often have long and steep grades. My 2016 GMC Sierra 2500HD 6.0L, 6-speed gasser did fine loaded with 1500lbs of payload, but when loaded with my 12,000lb 5th wheel (1,800lb pin), it struggled up in the hills. It always made it, but I'd be running at near redline and going ~40 mph. I was beating on it hard. I had to consistently be one step ahead of hills trying to get as much momentum going. The drive was not enjoyable. I decided it was time for a new truck and I needed the diesel. I upgraded to a 2022 Silverado 2500HD Custom with the Duramax. There is no comparison in power obviously. I now have the power to get me up the hills as needed without putting myself in a bad spot or severely backing up traffic. Is there more maintenance and cost associated with the diesel, yes. But it is worth it to me.

Now... all that being said... again, I live in Colorado and drive all around Colorado. If I lived at lower elevations and didn't have the mountains to deal with, I would have gone gas. I truly feel a diesel would have not been needed. The power output of the gas motors paired with the 10-speed auto transmissions it very impressive. That's all based on research as I have not driven a new gasser at lower elevations.

Hope this helps. Good luck with the decision.

BTW... Last month, I cleared 9.7mpg over 535.7 miles going from Denver, CO to Grand Junction, CO and back. That's going I-70 through the Rocky Mountains pulling the 5th wheel.

Edited July 26, 2023 by Elite130

asilverblazer · July 26, 2023

Something I don't see anyone talking about it... regrets...

There is no reasonable comparison in capability of the gas engine to diesel. You can get a gas engine and it can suffice just fine, but the diesel will do the same thing and perform better doing it.

So, you crunch all your numbers and decide that the gas engine is all you need.

Then spend the rest of your time owning it wishing you had gone ahead and gotten the diesel.

To the say the gas engine will work better in the city as a daily driver is pointless. My diesel 3500 is getting the same mileage as my 1/2 ton 5.3l did - both in the city and on the highway. These trucks are cumbersome in all but the most spacious of parking lots, impossible? No; but you're not whipping into any parking spots or nimbly darting through rush our traffic either.

The comfort level the diesel is going to bring when towing that size trailer will be a noticeable improvement over the gas.

4-By-4 · July 26, 2023

Reading through this thread, and other similar ones, it becomes really clear that there is no one "best" answer for everyone. I just recently got back into a GM HD truck, and did a lot of reading of just these type threads before I made my choice. My experience began with a 2003 Chevy 2500 with the big block, pulling a 21' toyhauler with a couple quads, weighing about 8.5K. It pulled it fine anywhere I wanted to go..up, down, around. Then I upgraded to a 34' toyhauler with a 2500lb car in the tail end, weighing over 12K IIRC. That became a white knuckle ride, especially downhill or in any sort of crosswind. So, I traded into a 2004 Dmax, and it was night and day better..more in control, and instantly I became an oil burner convert. After dealing with 8 years of the Chevy falling apart every couple months (but towing awesome when it worked), in 2012 I went with a RAM cummins, and my love affair continued until late 2020 when I had no need for such a big truck, and I (foolishly) sold it, thinking we were done with the RV thing.

Fast forward 3 years and the wife wants a small camper trailer (about 5.5K loaded), and I went with a 1/2 ton. I was right back to constantly worrying about weight, wind, etc. So, I started looking into the current HD's, and ended up landing on the new GMC. After reading about the hassles of the smog crud on the modern diesels, and planning to keep this camper, I think the gasser fits my use case. If I were going to be towing a 37+', 14K+ rv across country every year, I wouldn't hesitate, and would just have to deal with the potential issues of the diesel. It's heavier, and the engine braking would be a significant concern, especially going down the steep hills. Just get as long of an extended warranty as you can, and chalk up the expenses as the "cost of doing business". And I close by clearly realizing my opinion is worth exactly what you paid for it..Good luck with your tough decision!