MPG's with Diesel

[mtbackpacker]

A pretty interesting video was recently posted about towing mileage on The Fast Lane Trucks website... they hand calculated mileage, used the same loop, and a few other things to try and make the test as even as possible. The diesels had the best fuel economy in the test but not by much (not nearly as much improvement as many of the claims I have seen from my diesel fan friends over the years). Amusingly the 3/4 ton diesel pulled a bigger heavier trailer than the half tons and got a touch better mileage too. All in all worth watching.

Not positive on the policy linking to external sites like that but a quick Google will find it pretty quick.

[Specsalot]

Originally Posted by Countryboy59

My ram 6.7 diesel gets around 13 not towing, 11-12 towing. Gets driven about 1500 miles per year or less. If it got 8, I’d still love it.

Truth Countryboy59

'18 Ram 3500 DRW Aisin 6 SPD 4WD 3.73 CTD 25' FC RB - Still breaking it in, but the average is 13-13.5 towing @ 65 MPH. Comfort, Capacity, Visibility, Stability, Safety - Why I tow with this truck . . . Peace of Mind.

If you have any sense of the low quality of US LSD and the stress of modern HPFP CRD fuel systems, you will run at least a lubricity additive.

[Salvagediver]

Originally Posted by Specsalot

Truth Countryboy59

'18 Ram 3500 DRW Aisin 6 SPD 4WD 3.73 CTD 25' FC RB - Still breaking it in, but the average is 13-13.5 towing @ 65 MPH. Comfort, Capacity, Visibility, Stability, Safety - Why I tow with this truck . . . Peace of Mind.

If you have any sense of the low quality of US LSD and the stress of modern HPFP CRD fuel systems, you will run at least a lubricity additive.

I'll admit to being a bit OCD regarding engine/drive train maintenance and always used Howes "Diesel Treat" in our Freightliner chassis based Super C but have been doing the same with our new Cummins powered Ram 2500. Fully synthetic Shell Rotella goes into the crankcase. We tow an International Serenity 30RB using a ProPride 3P 1400 and have the auto-airlift rear suspension supporting a 3.73 LSD. I also use the STP diesel treatment on occasion even though all the truckers say "nothing is needed south of I 40" Another point recommended to me was to engage the exhaust brake in Auto always...not sure if any others have been advised the same way.

I do my best to avoid bio-diesel but am wondering what you use to care for your engine a keep the injectors in shape. Thanks.

[Jim Flower]

2014 Jeep 3L Diesel. 14.7 mpg on numerous trips between Florida and Ontario towing a 30. 28 mpg non towing on same trip. Jim

[gypsydad]

Originally Posted by Salvagediver

I'll admit to being a bit OCD regarding engine/drive train maintenance and always used Howes "Diesel Treat" in our Freightliner chassis based Super C but have been doing the same with our new Cummins powered Ram 2500. Fully synthetic Shell Rotella goes into the crankcase. We tow an International Serenity 30RB using a ProPride 3P 1400 and have the auto-airlift rear suspension supporting a 3.73 LSD. I also use the STP diesel treatment on occasion even though all the truckers say "nothing is needed south of I 40" Another point recommended to me was to engage the exhaust brake in Auto always...not sure if any others have been advised the same way.

I do my best to avoid bio-diesel but am wondering what you use to care for your engine a keep the injectors in shape. Thanks.

To the Automatic Engine brake question...one of the reasons to tow with a diesel, IMHO...I always engage with cruise control when towing our 28', and you really come to appreciate it in mountains. Airlift bags do nothing for handling/controlling with a heavy load...just levels out your rig...lots of videos on this; your suspension is your suspension...a good WDH with proper loading is most important in overall control. Make sure your within mfg. specs.

[Salvagediver]

Originally Posted by gypsydad

To the Automatic Engine brake question...one of the reasons to tow with a diesel, IMHO...I always engage with cruise control when towing our 28', and you really come to appreciate it in mountains. Airlift bags do nothing for handling/controlling with a heavy load...just levels out your rig...lots of videos on this; your suspension is your suspension...a good WDH with proper loading is most important in overall control. Make sure your within mfg. specs.

I agree absolutely; the engine brake was a key attribute for me in addition to gobs of good ol' 'Merican TORQUE...especially after smelling overheated brakes on others on long grades. We have plenty of excess capacity in our TV because Airstreaming is supposed to be relaxing, right? I mean, isn't that the Prime Directive?

[KelloggKid]

Hans627 - There are way too many variables to give you a good answer. As you can imagine, a lot depends on which diesel, what you are hauling/pulling, transmission, differential, type terrain, driving habits, etc.

That said one thing you can count on is your RAM will get better mileage when it is broken in. With only 4,000 miles on your rig it is still very tight. I have about 270,000 on my Cummins and my overall average mileage in all conditions is 16.8 mpg. I'm a bit of a lead foot so probably could have done better.

[Hans627]

Originally Posted by Salvagediver

I'll admit to being a bit OCD regarding engine/drive train maintenance and always used Howes "Diesel Treat" in our Freightliner chassis based Super C but have been doing the same with our new Cummins powered Ram 2500. Fully synthetic Shell Rotella goes into the crankcase. We tow an International Serenity 30RB using a ProPride 3P 1400 and have the auto-airlift rear suspension supporting a 3.73 LSD. I also use the STP diesel treatment on occasion even though all the truckers say "nothing is needed south of I 40" Another point recommended to me was to engage the exhaust brake in Auto always...not sure if any others have been advised the same way.

I do my best to avoid bio-diesel but am wondering what you use to care for your engine a keep the injectors in shape. Thanks.

Just curious about your comment about using the exhaust brake in Auto always. Why would that be the recommendation?

[wbrisett]

Originally Posted by mtbackpacker

Not positive on the policy linking to external sites like that but a quick Google will find it pretty quick.

TFL does a great job of trying to make everything equal. Doesn't always work, but it's still impressive.

For the record, we just updated our tow vehicle to a 2020 Chevy ¾ ton Duramax, with our 2015, we would get 16-17 empty and 10-12 towing our AS. We haven't broken in the diesel engine yet, but empty we're actually getting 18-20 MPG, and 10-13 towing so far. The increase when empty I'm racking up to the new 10-speed transmission (they are also doing some better engine management from what I understand). I was hoping to see better when towing, but maybe that will come when we break the engine in more. Or it could be we just don't see much gain there even with the updated engine management since we're towing a fairly moderate load.

[Salvagediver]

Originally Posted by Hans627

Just curious about your comment about using the exhaust brake in Auto always. Why would that be the recommendation?

That recommendation came by way of a three time Dodge/Ram Cummins driver who told me his independent diesel mechanic recommended that. I then asked the local Ram Service Manager about what I was told, and he stated it was a good idea...I suppose it helps to keep the turbo from coking up??? I haven't searched any Ram forums to confirm...but I could see the logic. Some of my experience in the Navy with Cat D-399's and EMDs main propulsion diesels and ship's service diesel generators were to always try to keep a good load (80%) to keep the turbos from getting cruddy...so maybe using the exhaust brake can help somehow in the same way. But we were also tracking FO dilution in the lube oil (concern was for crankcase explosions); "sweetening" the lube oil on occasion, pop tests on the injectors, dosing the FO to keep bugs from growing and other tests for Trend Analysis reasons...and that's probably why I am so stupidly OCD about diesel maintenance...the Navy programmed me and I'm helpless to stop concerning myself; perhaps professional counseling is in order ;-)...

In any case, I've used the auto function to maintain a steady speed down long grades and the "Full" setting to reduce speed on grades. As an aside, I asked the Service Manager where he was seeing failures with the Cummins, and he told me the only turbo repairs he has seen were from guys who overload their trucks and run them fast for extended periods - but even then the most recent was a five year old 3500 with over 180,000 miles. He said it was typically a 3500 or 2500 DRW truck hauling a long car carrier who tend to push the speed for long periods. The Parts Manager confirmed he wasn't stocking many wear items or stock for common failures though he kept some turbos and injectors on the shelf...otherwise, he just maintained a reserve of filters (which he then told me to buy off Amazon).

[crispyboy]

Originally Posted by Hans627

Just curious about your comment about using the exhaust brake in Auto always. Why would that be the recommendation?

The Cummins engine in your truck uses a Holeset variable geometry turbo. The vanes and sliding nozzle must be kept free of soot and the best way to do this is to use the exhaust brake on a regular basis. If the soot load becomes to great it will overload the electric actuator (moves the sliding nozzle on the turbo) and will fail. The only preventative maintenance to this is to use the exhaust brake and periodically tow a heavy load.
The 2007.5 thru 2012 trucks had high soot loads due to the extreme amounts of EGR gases allowed in the emission strategy. This in turn would necessitate at turbo replacement. This is the main reason people would delete emission components - unreliable emission components.

The 2013 and newer trucks use the DEF fluid and there is much less EGR gases in the emission strategy. Most 2013 and newer truck owners will leave emissions intact because the system is more reliable and turbos last much longer.


http://www.myholsetturbo.com/vgt.html

[Salvagediver]

Great site! Thanks!!

[DewTheDew]

I have a stupid question that I'm just going to tack on here (since we are talking about fuel and diesels) rather than start another thread. I've had a diesel car for a long time but rarely need to fill it other than locally (it has almost a 600 mile range!) as we do not often take long trips in it. Now that we have a new diesel truck to haul the trailer where I am driving farther, I found myself a bit confused stopping to fill up on our recent trip from DC to Florida and back regarding filling where the big rigs are.

Some gas stations along the interstates are essentially truck stops (Flying J and so forth) and it seems that most, if not all, the diesel pumps are in lanes for the semis. Can I fill up there? Once I happened to see a sign on one pump by the semis that said "RV diesel" so I used that but another time the only diesel pumps were in the Semi lane. Not talking about off-road/farm diesel here. I googled and it seems the difference is the tax. The one time I filled in the big rig lane I had to pre-pay and I think she put in a different rate but I'm not sure (on the good side, those pumps have a huge nozzle and high-volume pump for a fast fill!).

Anyway, what is the protocol? The problem is that each time I am pulling into an unfamiliar station trying not to hit anything or get stuck someplace that I have to back out of so I am a bit tense. As mentioned, I did fill from the big rig lane once and everything was fine, but I was just not sure and thought I would ask. What say you? Thanks!

[Salvagediver]

Originally Posted by DewTheDew

I have a stupid question that I'm just going to tack on here (since we are talking about fuel and diesels) rather than start another thread. I've had a diesel car for a long time but rarely need to fill it other than locally (it has almost a 600 mile range!) as we do not often take long trips in it. Now that we have a new diesel truck to haul the trailer where I am driving farther, I found myself a bit confused stopping to fill up on our recent trip from DC to Florida and back regarding filling where the big rigs are.

Some gas stations along the interstates are essentially truck stops (Flying J and so forth) and it seems that most, if not all, the diesel pumps are in lanes for the semis. Can I fill up there? Once I happened to see a sign on one pump by the semis that said "RV diesel" so I used that but another time the only diesel pumps were in the Semi lane. Not talking about off-road/farm diesel here. I googled and it seems the difference is the tax. The one time I filled in the big rig lane I had to pre-pay and I think she put in a different rate but I'm not sure (on the good side, those pumps have a huge nozzle and high-volume pump for a fast fill!).

Anyway, what is the protocol? The problem is that each time I am pulling into an unfamiliar station trying not to hit anything or get stuck someplace that I have to back out of so I am a bit tense. As mentioned, I did fill from the big rig lane once and everything was fine, but I was just not sure and thought I would ask. What say you? Thanks!

Many times the larger truck stops will have pumps specifically for RVs so you should go to those if available vice the pumps for the "big rigs"...after all, they are trying to make a living and are paid by the mile (normally around .50/mile) so need to fuel and go. Pro truck drivers need to use their available drive time efficiently since they may be in a lease or are an independent paying maybe $1500-$2000/month for their tractor rain or shine. Beware, usually the RV island has both diesel and gas!!

Here is the key: if only the diesel pump islands the truckers use are available, get in, fuel and move out of the way. You'll notice a yellow line is painted ahead of the fuel pumps. If the clerk at the fueling desk doesn't charge a specific amount on your card in advance and you must return to fetch your card FIRST move your rig up to the yellow line after fueling. Then, any trucks waiting behind you can advance up to the pumps to start refueling. Obstructing the pumps whilst you go into the Flying J to grab your card, buy a big cup o' Joe and use the head is a fine way to PO the truck driver behind you in line who may then be encouraged to see RVers in their "turf" as being brainless, inconsiderate mouth-breathers.

Same with signalling lane changes ALWAYS, and switching off your headlights momentarily to indicate they are clear to return to the right hand lane when they are passing YOU. When they notice they are generally appreciative and blink the "ICC lights" to give thanks. Maybe y'all know all that code...

Many of the line haulers are governed to 60 or 62 MPH...some seem to find their most efficient speed based on final gearing at 67 MPH. I think the TMC drivers are governed to 60 and Prime is 65... So if you are slower, I humbly recommend you stay in the right hand lane and never camp-lane out in the left and jam up traffic...ESPECIALLY on the two lane portions of I95 in North and South Carolina (or anywhere obviously) where frustration can build before entering the three lane sections for example in GA and FL.

One more pro tip: since you are heading south from the District, NEVER speed in/around Emporia, VA...just north of the NC border on the 95! Same with the stretch of 301 north and south of Waldo in FL if crossing over to the west coast from JAX to Ocala to get to I75 from I95; a notorious speed trap, especially for Yankees.

[gypsydad]

Originally Posted by DewTheDew

I have a stupid question that I'm just going to tack on here (since we are talking about fuel and diesels) rather than start another thread. I've had a diesel car for a long time but rarely need to fill it other than locally (it has almost a 600 mile range!) as we do not often take long trips in it. Now that we have a new diesel truck to haul the trailer where I am driving farther, I found myself a bit confused stopping to fill up on our recent trip from DC to Florida and back regarding filling where the big rigs are.

Some gas stations along the interstates are essentially truck stops (Flying J and so forth) and it seems that most, if not all, the diesel pumps are in lanes for the semis. Can I fill up there? Once I happened to see a sign on one pump by the semis that said "RV diesel" so I used that but another time the only diesel pumps were in the Semi lane. Not talking about off-road/farm diesel here. I googled and it seems the difference is the tax. The one time I filled in the big rig lane I had to pre-pay and I think she put in a different rate but I'm not sure (on the good side, those pumps have a huge nozzle and high-volume pump for a fast fill!).

Anyway, what is the protocol? The problem is that each time I am pulling into an unfamiliar station trying not to hit anything or get stuck someplace that I have to back out of so I am a bit tense. As mentioned, I did fill from the big rig lane once and everything was fine, but I was just not sure and thought I would ask. What say you? Thanks!

First, we have found the Flying J and Pilot stations are typically a dime or more expensive per gallon, even with the Good Sam card discount, than other stations that sell diesel. So we don't go to those "big truck" stations for that reason.
We can usually find diesel much cheaper at standard gas stations that have diesel advertised on their signs, near by...Our GPS in our F250 shows us the stations with diesel and also shows pricing at most of them, so we can decide where to stop. I carry DEF on long trips in the back from Walmart, and I also keep a stash of cloth/rubber disposable gloves on hand under my rear seat. I keep one stashed by the filler valve behind the gas cover panel, and it lasts quite a while...not a big deal to avoid the big truck stations/lanes...just watch your gauge and fill when close to 1/4 full or "earlier" if you see a good price!

[Salvagediver]

Originally Posted by gypsydad

I carry DEF on long trips in the back from Walmart

Gypsydad; Appreciate your informative posts! Our Freightliner/Super C had Tier II power so no DEF requirement and consequently this is a new aspect to me. I've been using "Blue" DEF, but am not sure if there is much difference in quality. But since that's what they serve at the pumps, I figured it was as good as any. Do you have a preference? Are there any storage concerns? I am hearing to not leave the stuff in a hot garage for example...sorry to deviate from the MPG thread (again).

Thanks in advance, and hope we see you "out there" one day.

[gypsydad]

Originally Posted by Salvagediver

Gypsydad; Appreciate your informative posts! Our Freightliner/Super C had Tier II power so no DEF requirement and consequently this is a new aspect to me. I've been using "Blue" DEF, but am not sure if there is much difference in quality. But since that's what they serve at the pumps, I figured it was as good as any. Do you have a preference? Are there any storage concerns? I am hearing to not leave the stuff in a hot garage for example...sorry to deviate from the MPG thread (again).

Thanks in advance, and hope we see you "out there" one day.

Thanks; right now we are camped at Goose Island, Rockport TX....very nice state park with free showers....but I digress.

For my F250, I go thru DEF faster when towing at speed, then when not towing around town, so thats the only reason I carry an extra 2.5 gal container. The F250 will take 5 gal if it is way down on the gauge, but it's nothing to me to get to a Walmart typically. I have, on occasion, purchased from other places when I was down below 1/3 full on the gauge. There are some concerns about heat and cold I have read; also folks caution about the dates and storage....not sure their are "big" differences in mfg/brands, however. This works for me and not a big deal to get it when I need it.

I'm sure someone here can light up a conversation on all this with more knowledge about this with more actual data...

[Salvagediver]

Originally Posted by Hans627

That's the best mpg's I've ever obtained and just wanted to share. And it made me curious about the best mpg's you've achieved when towing with a diesel TV?

Hans,

Just cleared 1,000 miles on our 19 Ram 2500 Cummins and made a run up I-75 to Ocala National Forest today from St. Pete and back and achieved 20.1 MPG with a combination of city and road travel with the cruise set for 73 MPH. We have the six speed, 3.73 LSD and 20" tires, and a Retrax bed cover. I felt the mileage was decent given the combination of city and road travel and especially the stop-and-go on 275 from the Howard Frankenstein Bridge across Old Tampa Bay through to North of Tampa (including on the way back south). I do use a fuel additive for improved lubricity/injector care.

[sbowman]

Originally Posted by Hans627

I don't want to start a gas vs. diesel debate as both are great TV's in the right circumstances (which you get to determine). Nor do I wish to have a "my truck is better than your truck" discussion. Again all trucks these days are awesome machines.

I have a 2019 RAM 2500 with the Cummins diesel with about 4000 miles on it. We are on our way to FL from PA traveling I-95. Yesterday, driving in relatively flat NC and SC, I got 14.8 mpg driving at 65 mph and towing the AS. This was calculated manually, 302 miles divided by 20.4 gallons (the onboard computer is always more optimistic).

That's the best mpg's I've ever obtained and just wanted to share. And it made me curious about the best mpg's you've achieved when towing with a diesel TV?

2016 RAM 3500 4x4 4 door long bed w/topper just under 9k w/26k. Towing loaded 19k weight in motion lowest 11.5 best 16.2. Not towing over 22. Living in the PNW we travel up and down. Not a lot of flat land.



Best regards

[Salvagediver]

Originally Posted by gypsydad

First, we have found the Flying J and Pilot stations are typically a dime or more expensive per gallon, even with the Good Sam card discount, than other stations that sell diesel. So we don't go to those "big truck" stations for that reason.
We can usually find diesel much cheaper at standard gas stations that have diesel advertised on their signs, near by...Our GPS in our F250 shows us the stations with diesel and also shows pricing at most of them, so we can decide where to stop. I carry DEF on long trips in the back from Walmart, and I also keep a stash of cloth/rubber disposable gloves on hand under my rear seat. I keep one stashed by the filler valve behind the gas cover panel, and it lasts quite a while...not a big deal to avoid the big truck stations/lanes...just watch your gauge and fill when close to 1/4 full or "earlier" if you see a good price!

GD,

I'm researching a means to use a logistics provider's fuel card that allows for discounted fuel purchases at Love's, Flying J, and TA and will update this thread if this works out...