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Old 10-27-2018, 11:05 PM   #1
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Gas Mileage

Hi Folks,

Iím the proud owner of a brand new 5th wheel, a FR Sabre, 30RLT. I imagine that someone has already asked this question, but a search didnít show up anything.

Yesterday I pulled my new trailer about 125 miles and was shocked by the lousy gas mileage. I was getting 3 kms per litre or for my American friends, 7.1 miles per gallon! I have a GMC Sierra 3500 HD (6l gasoline engine). So far I have not loaded the trailer with more than about 600 lbs, so Iím way below the load limit. Every little hill and the truck would down shift and the engine would be running around 4500 to 5000 RPM. I tried using the ďtrailer modeĒ to see if that made any difference (it didnít). Iíve always used regular gas in my truck, so I donít know if a higher octane fuel would help (comments anyone?).

Any thoughts on whether this is typical? Should I change fuel octane? Do I need to purchase a larger fuel tank (mine is only 35.7 gallons)? Do I need to purchase a diesel truck?

Any and all helpful comments are welcome.

Cheers,

Bruce
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Old 10-27-2018, 11:08 PM   #2
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Give it a few toes before you make a change.

My first towing with my new 2018 Ram diesel was about 180 miles with a majority of it being backroads. I about crapped myself when I calculated mileage at 6.7 mpg.

Now that I have a few more pulls- I just checked my last towing and it was 9.7mpg.

I’m happy with anything over 9.

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Old 10-27-2018, 11:37 PM   #3
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Hi Ependydad,

Is yours a diesel truck?
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Old 10-27-2018, 11:50 PM   #4
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While a diesel would help, maybe 10 or 11 MPG, it is a $9,000 or so option. I am a very careful driver and my 2019 F350, CC, longbed, diesel, almost always stays below 1,800 RPMs. I don't go over 65 miles per hour and always have slow takeoffs. My fuel tank is also 37.5 gallons and since I don't often go over 300 miles per day it does the job. Good Luck
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Old 10-28-2018, 05:24 AM   #5
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A couple of things...

I considered adding more fuel... I can drive all day but I like to get out of the truck after about 200-250 miles which is near enough to refuel time. So I skipped adding any more fuel holding ability.

A slightly higher octane is not likely going to help you any noticeable way. E85 (if capable) actually makes the 6.0 have a little more horsepower and torque but you will get less fuel mileage (I haven't tried it).

Tow haul will have little effect on the highway at this much weight. It will help you out more if going through a town where you will be changing speeds more often.

What year truck?
What rear end ratio 3.73 or 4.10?
Stock rims and tires are important...if you went larger it will hurt performance/force downshifts more often.

The trailer you bought is near the maximum for a modern GM HD with the 6.0l and the gpm's seem right in line with my 6.0liter truck pulling a 9500lb trailer at about 73mph. It gets better if you drive slower but expecting double digit mpg's is outside the norm with that much weight. Of note is that my truck is the first vehicle I've had that the onboard computer calculation for mpg while towing is showing lower than when using hand calculation -most are the other way around and I don't know if that is normal with this truck/transmission/rear end/ or if its just my truck. The display shows about .5 less than actual.

On the shifting...It took a couple of hundred miles for my truck to settle in while pulling at highway speeds the first time. I'm sure the transmission has 'learned' some and I have adapted some also. If you approach a 'hill' with the cruise on it will almost always drop speed initially enough to force a downshift. I've found that getting in the gas before the hill will allow the truck to stay in overdrive (5th) for most hills. If the hill is fairly steep it will downshift to 4th which is about 3,800 rpm at ~ 70mph. The only time I recall it downshifting to 3rd was once (maybe a couple times) in the mountains and only once did I find a grade that slowed the truck to less than 70mph.

Again, that is with my truck and trailer. 2017 double cab / long box / 6.0 / 4.10 rear end / with the smallest rims GM puts on it (this helps).

You asked if you needed a diesel truck...I could have written the check for the diesel same as the truck I chose and if I could go back in time I would buy the same gas truck. Modern diesels are awesomely powerful but unfortunately they have lost their greatest benefit. They are now very complicated (emissions) and reliability suffers. My friend at work left a job about two years ago where he supervised a fleet of HD trucks. They had Ram, Chevy and Fords. The amount of warranty work being performed on these trucks was causing downtime issues for the business so they switched to gas and haven't looked back. A local sewer and water company near me switched to all gas trucks as well. You don't need a diesel. That gas truck will take you anywhere the diesel will and the chances are better that it will not have any reliability issues but you may want one. I love power and speed...not at the expense of reliability in a tow vehicle though.

Welcome here and good luck with your truck and trailer.
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Old 10-28-2018, 06:35 AM   #6
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I have a 15 2500 with the 6.0. I pull through the mountains in ny. I run e85 and in the mountains i see 5 to 6mpg. The higher the engine revs the more fuel.you use. These 6.0 love to spin, thats where they make their power unlike the diesels where they make it down low. I dont tow all the time and from what i read about regen, my short trip driving around town would kill the diesel. I carry an extra 25 gallons of gas (e85) with me for my return trip sinve its not readily available.
As far as a larger tank, have not found 1 for gas.
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Old 10-28-2018, 07:09 AM   #7
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Hello Bruce
Being you are in Calgary are you on flat land or foot hiils? I know that higher octane helped with my 5.4 l Ford F 150 truck with performance but added cost did not make up with mileage. I am in diesel truck now for the last two. As much as some state major issues with modern diesels I have not seen this. Commercial use does not equate personal use with any truck. Maybe talk with other people towing in your area of travel to get an idea on what to expect.
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Old 10-28-2018, 07:35 AM   #8
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Originally Posted by WhiteEagle View Post
Hi Folks,

Iím the proud owner of a brand new 5th wheel, a FR Sabre, 30RLT. I imagine that someone has already asked this question, but a search didnít show up anything.

Yesterday I pulled my new trailer about 125 miles and was shocked by the lousy gas mileage. I was getting 3 kms per litre or for my American friends, 7.1 miles per gallon! I have a GMC Sierra 3500 HD (6l gasoline engine). So far I have not loaded the trailer with more than about 600 lbs, so Iím way below the load limit. Every little hill and the truck would down shift and the engine would be running around 4500 to 5000 RPM. I tried using the ďtrailer modeĒ to see if that made any difference (it didnít). Iíve always used regular gas in my truck, so I donít know if a higher octane fuel would help (comments anyone?).

Any thoughts on whether this is typical? Should I change fuel octane? Do I need to purchase a larger fuel tank (mine is only 35.7 gallons)? Do I need to purchase a diesel truck?

Any and all helpful comments are welcome.

Cheers,

Bruce
Changing to a higher octane will not increase mileage. I take it that the rear gear ratio is 4:10 and that was the only option with the 6.0. Using tow haul may help in better mileage. I had a 2500 6.0 and the best I could get towing was 9.0 mpg but My trailer lighter than your 5er. As mentioned get a few more towing miles on the tv and you may do a little better on mileage. also keep the speed to around 62 as that is where I got the best mileage. Also the higher RPM is typical of this engine and that what it is made to do when ascending hills. Some folks get up set with the high engine noise but that is the nature of the 6.0.



If your not satisfied with the mileage then consider a diesel but here again how much towing will you do to justify the 9grand more for the truck. Later RJD
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Old 10-28-2018, 07:52 AM   #9
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Hi Bruce!
I bought a new Nissan Titan 5.6L last Dec 23. Nice Christmas present for me!
In January this year we hitched up my 29' ~6000 LB trailer and headed south on a frosty 6 Deg F morning. We were headed from Louisville KY to Port Lucy FL. I was shocked to get just about the same MPG as you report! Low 7s.

How I wish I had your 37 gallon fuel tank! Mine is only 26 us gal.

2 thoughts... you didn't drive far enough to get a good measurement. You need to test it over at least a couple of fill ups.
AND you didn't mention hills or head wind or how fast you were going.

This summer in June-July we towed from our home north to near Wisconsin Dells and then turned left and went all the way across northern US to Anacortes Washington then down the west coast highway thru Yosemite and AZ back to Kentucky
We drove 7532 miles
burned 814 gallons of regular gas
averaged 9.25 mpg

But- going west across Wyoming with a fierce head wind we got 6.5 mpg!!
Going down the coast highway drafting my friends motor coach we got as high as 13.
Just a little head wind or tail wind makes a difference. Speed kills your mpg. You can slow down 10 mph and gain 2 mpg.
I have been known to draft semis when the headwind is bad and traffic allows.

A Diesel adds $10000 or more and adds maintenance cost and even higher insurance.

Don't get lost in the "should I have a diesel" argument just yet.
Give that gasser a chance while you learn how to stroke it and get better MPG.

Good luck! Happy Camping!
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Old 10-28-2018, 08:29 AM   #10
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In defense of the added cost of a diesel. It is less than $10,000. No one pays list price either.

And, check NADA. For the most part you get your money back on resale.

Pulling about #15,000 we get 11 mpg at 64mph(4,000 miles). It is stress free. That was my observation of going to diesel. No downshifting on every hill.

Your mileage sounds about normal. In the 60’s the one ton dual tire trucks I drove like yours had a big in line six. Their mileage was worse. First stop every morning was the gas pump.
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Old 10-28-2018, 08:50 AM   #11
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Originally Posted by WhiteEagle View Post
Hi Folks,



Iím the proud owner of a brand new 5th wheel, a FR Sabre, 30RLT. I imagine that someone has already asked this question, but a search didnít show up anything.



Yesterday I pulled my new trailer about 125 miles and was shocked by the lousy gas mileage. I was getting 3 kms per litre or for my American friends, 7.1 miles per gallon! I have a GMC Sierra 3500 HD (6l gasoline engine). So far I have not loaded the trailer with more than about 600 lbs, so Iím way below the load limit. Every little hill and the truck would down shift and the engine would be running around 4500 to 5000 RPM. I tried using the ďtrailer modeĒ to see if that made any difference (it didnít). Iíve always used regular gas in my truck, so I donít know if a higher octane fuel would help (comments anyone?).



Any thoughts on whether this is typical? Should I change fuel octane? Do I need to purchase a larger fuel tank (mine is only 35.7 gallons)? Do I need to purchase a diesel truck?



Any and all helpful comments are welcome.



Cheers,



Bruce


That sounds about right for a gas engine. If you want your truck to pull better then get a diesel. But thatís around ten thousand dollars more and unless you do a whole lot of driving you will never get that money back plus diesel cost more
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Old 10-28-2018, 08:56 AM   #12
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Hi Bruce!
I bought a new Nissan Titan 5.6L last Dec 23. Nice Christmas present for me!
In January this year we hitched up my 29' ~6000 LB trailer and headed south on a frosty 6 Deg F morning. We were headed from Louisville KY to Port Lucy FL. I was shocked to get just about the same MPG as you report! Low 7s.

How I wish I had your 37 gallon fuel tank! Mine is only 26 us gal.

2 thoughts... you didn't drive far enough to get a good measurement. You need to test it over at least a couple of fill ups.
AND you didn't mention hills or head wind or how fast you were going.

This summer in June-July we towed from our home north to near Wisconsin Dells and then turned left and went all the way across northern US to Anacortes Washington then down the west coast highway thru Yosemite and AZ back to Kentucky
We drove 7532 miles
burned 814 gallons of regular gas
averaged 9.25 mpg

But- going west across Wyoming with a fierce head wind we got 6.5 mpg!!
Going down the coast highway drafting my friends motor coach we got as high as 13.
Just a little head wind or tail wind makes a difference. Speed kills your mpg. You can slow down 10 mph and gain 2 mpg.
I have been known to draft semis when the headwind is bad and traffic allows.

A Diesel adds $10000 or more and adds maintenance cost and even higher insurance.

Don't get lost in the "should I have a diesel" argument just yet.
Give that gasser a chance while you learn how to stroke it and get better MPG.

Good luck! Happy Camping!


Thatís the first time I ever heard that the insurance is higher on a diesel. I normally just keep the tank full myself. There is three things men will lie about, one is the size of fish, one is there fuel mileage and something else
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Old 10-28-2018, 09:10 AM   #13
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Hi Folks,

I’m the proud owner of a brand new 5th wheel, a FR Sabre, 30RLT. I imagine that someone has already asked this question, but a search didn’t show up anything.

Yesterday I pulled my new trailer about 125 miles and was shocked by the lousy gas mileage. I was getting 3 kms per litre or for my American friends, 7.1 miles per gallon! I have a GMC Sierra 3500 HD (6l gasoline engine). So far I have not loaded the trailer with more than about 600 lbs, so I’m way below the load limit. Every little hill and the truck would down shift and the engine would be running around 4500 to 5000 RPM. I tried using the “trailer mode” to see if that made any difference (it didn’t). I’ve always used regular gas in my truck, so I don’t know if a higher octane fuel would help (comments anyone?).

Any thoughts on whether this is typical? Should I change fuel octane? Do I need to purchase a larger fuel tank (mine is only 35.7 gallons)? Do I need to purchase a diesel truck?

Any and all helpful comments are welcome.

Cheers,

Bruce
My 6.0 likes mid grade much better . Also just recently had to replace an exhaust manifold went with a performance header . Wish I did it yrs ago power gain was good . Where it would have grabbed 2gearswhen climbing it now only grabs 1 . Best up grade ever . Low and mid range greatly improved. Mpg up by 1 . Or just under 10%
Also by the sound of it your using cruise . Every little hill shouldn’t change a thing and not drop that many gears . Only time mine runs 4500 is over vail pass or Ike tunnel
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Old 10-28-2018, 09:17 AM   #14
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That’s the first time I ever heard that the insurance is higher on a diesel. I normally just keep the tank full myself.

My new Titan-- $35,000
New Diesel ~~ $50,000
Insurance is higher because collision repairs on a more expensive truck are higher. Also higher tax.

We kept meticulous records and did the math every stop as well as totals after the trip. I'm not exaggerating my MPG. They are the real numbers.
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Old 10-28-2018, 10:02 AM   #15
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I have had diesels since Dodge came out with their first one. Thatís when I purchased a ram 2500. Had them since then until I recently changed to a gasser for 2019.
This is what I found of many years having one. Unless you will be towing heavy rigs a lot itís not worth it. Diesel fuel in my area is now 50 cents a gallon more. Maintenance on a diesel has went sky high. Oil change $100-$150 then add the change of fuel, oil, and other filters 300-400. The added cost of the Diesel engine is 9000-10000 depending on brand. So with all the added cost upfront and additional maintenance cost I went to a gasser. Since I donít tow a lot any more. One other reason to think about a diesel is now with the new emissions system there has been issues with them. I know from experience itís not fun being stranded on the side of the road waiting on a tow truck.

But it is all up to you on what you want.
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Old 10-28-2018, 10:12 AM   #16
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Several folks have asked what my driving conditions were, so here goes:

85 kms/hr (50 miles/hr)
Rolling foothills (East slope of the Rocky Mountains)
Cross wind (roughly 22 miles/hr from the West) - travelling southbound
Used cruise control -> will try manual and speed up for the hills
Tried trailer haul mode but noticed that the RPMís climb going downhill (engine braking)

As a side note, I owned a Host 10.5 foot camper with two slide outs for three years prior to this, and my gas mileage averaged around 10 miles/gallon at 55 miles/hr (it was a very heavy camper). I know that we canít compare the two, so thatís not the purpose, but I wanted to give some context to my query.

This is a 2011 GMC 3500, and the axel is indeed 4.10

So now Iím wondering if Iím driving too slow. Maybe I should drive at the speed limit and see how things go.
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Old 10-28-2018, 10:45 AM   #17
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Several folks have asked what my driving conditions were, so here goes:

85 kms/hr (50 miles/hr)
Rolling foothills (East slope of the Rocky Mountains)
Cross wind (roughly 22 miles/hr from the West) - travelling southbound
Used cruise control -> will try manual and speed up for the hills
Tried trailer haul mode but noticed that the RPMís climb going downhill (engine braking)

As a side note, I owned a Host 10.5 foot camper with two slide outs for three years prior to this, and my gas mileage averaged around 10 miles/gallon at 55 miles/hr (it was a very heavy camper). I know that we canít compare the two, so thatís not the purpose, but I wanted to give some context to my query.

This is a 2011 GMC 3500, and the axel is indeed 4.10

So now Iím wondering if Iím driving too slow. Maybe I should drive at the speed limit and see how things go.
I don't care for the truck to downshift going down hills by its programming. If I want engine breaking I will tell it to shift down... but I'm not sure if the electronics on your truck work the same as mine. -With tow/haul on and the gear selector in manual it keeps the transmission from downshifting on hills/grades.
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Old 10-28-2018, 10:56 AM   #18
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Don't read too much into one short trip on a windy day. You will average from 7-9 mpg over many trips. Engine braking is not using any gas, it is just pumping air trying to slow you down.
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Old 10-28-2018, 11:23 AM   #19
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My new Titan-- $35,000
New Diesel ~~ $50,000
Insurance is higher because collision repairs on a more expensive truck are higher. Also higher tax.

We kept meticulous records and did the math every stop as well as totals after the trip. I'm not exaggerating my MPG. They are the real numbers.


Well for starters Iím not pulling my Cedar Creek with a titan. I just donít believe people telling me what fuel mileage there are getting. The only way I would believe anyone is if I was riding along, not happening. DW Mercedes insurance is higher than your titan and it pulls nothing.
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Old 10-28-2018, 11:55 AM   #20
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Fuel mileage goes all over the board for any truck. I pull a 5th wheel with a diesel and get 8-12mpg depending speed, wind, and hills. I pulled a car hauler weighing 7,000 lbs over 2,000 miles and got 8-15mpg. The days of 8mpg it was a strong head winds and on the last day I had 15 mpg because of a huge tail wind. For the story tellers, we need the facts......speed...wind.....hills. Speed some times has a sweet spot like 62 mph where the truck shifts to high gear and doesn't down shift much. Wind of 20 mph headwind and 20 mph tailwind could mean a difference of 40 mph. Hills even going slightly down hill or up hill for a longer way changes things. I headed south out of Cheyenne dropping over 1,000 ft elevation with maybe a tailwind and I got 14mpg the first hour with my 5th wheel. So conditions do make the difference.


With 25,000 miles of towing over the past 4 yrs I've seen a lot of different situations including blended winter diesel fuel vs 100% number 2.
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