i guess I want it all. I want fuel economy, and range, while towing, but also want confort & luxury to boot, and do not want to limit myself for any possible future towing. I currently own a 26' Travel Trailer Toy Hauler that weighs roughly 8500 lbs full. My current tow vehicle just can't cut the mustard ('03 Expedition). I'd like tom ove on to a Power Stroke. 7.3L, 6.0L, or 6.4? Which is best? How does an 06-07 6.0L compare to a 7.3L regarding fuel economy, cost of onwership, and reliability? I've heard all of the injector & EGR horror stories, burt I presume those are more centered sroung the '03-04 (and some 05) model years. I also MIGHT upgrade to a 5th wheel touy hauler, in the future (HEAVY!!! 11-15000 lbs). Should I go F350 now or F250 and add additional leaf springs? I prefer the interiors of the 05s, and newer.

Quite the dillema...which way do I go?

 

Since I've repeatedly heard the F250 and F350 have the same springs and rear axle (as well as everything else) I'd say buy whichever is the best deal. As for which diesel, I'd say the 7.3 seems to be the most reliable and likely the one I'd buy. They are harder to find these days with low mileage, but there's a super-nice 7.3 Super Duty on a local lot here that looks to have spent it's whole life being waxed and pampered.

 

This will also be my daily driver. The interiors of the pre '05 seem so dated...there was no Harley, or King Ranch trim avaialble yet either.

 

Then by all means roll the dice and get a 6.4 and learn to live with the 11mpg and the very real possibility of serious problems. The '09 6.4 regular cab SD's we have at work have lots of power, but also get worse mileage than my V10. But the interior does look nice.

 

Man, this is a fair and tough question. I am going to plug the '08 and newer 6.4.

Cons first:

Your MPG's will be 8-11, depending on gearing and driving style. You will fill 'er up every 220 miles.

2 fuel filters, 10,000 mile service interval. A little pricey and hard to find a mechanic outside of a dealer that is familiar with them and uses OEM filters.

5,000 mile oil changes. A little pricey if you don't do it yourself. If you do it yourself, every 5K can get old if you drive a lot.

Radiators are the biggest weak link. They only last 30-60K miles. When it leaks, it's slow enough to fool you and if you run low on coolant and bake an EGR cooler, your engine will endure a catastrophic failure.

The 6.4 is a "new diesel". New technology, lots of emissions control devices on the motor that can destroy it if you don't catch the warning signs. If you get one, learn as much about it as you can. The 6.4 forum is going very well, lots of activity and good advice. You might want to read the "tech folder" as you try to figure out what to get.

You should have an F350 SRW or higher if you plan on getting the big 5er. You could get by with a 250 (I do) with air springs on the rear axle but you would be overloaded. The main crux is the rear diff. 3.73 is ideal, 3.55 is probably not good, 4.10 is great but with each you get a big difference in MPG. Hard to weigh the pros and cons on this.

Pros:

'08 and newer interiors are great.
Transmission is rock solid.
Truck in general is heavy, best tow vehicle out there.
Tow Command system rocks.
6.4 is quiet, smooth, powerful, and does not "smoke" so you won't have to wash the passenger side of your trailer every week.
Longevity? I put a lot of miles on mine and the motor and emissions stuff are working just like it did when it was new.

Generally, if you are going to drive the truck every day and take it on trips with your RV I would stay '06 and newer, for lots of reasons. If it is going to be rarely used, you might find a "cherry" 7.3 out there but it's very hard to do nowadays.

Somebody is going to ask you "Why don't you get a V10?" You may want to think about this too.

 

6.4L is that bad? How's the 6.0/7.3? UInloaded, and also towing? I've heard the 6.0 & 7.3 can get 20-21 mpg unloaded, and can even get 16 towing? What have you experienced?

 

8-11 towing. Unloaded, 13-15 city, 17 highway unless you really baby it. Might eek out 18/19 in the best of conditions.

Now, you could take the emissions stuff off the tailpipe (DPF and CAT) and run a Spartan tuner. You could run at 550HP and nearly 1000ft/lbs of torque and get better mileage. I don't know how good the mileage is with the tuner, but it's better.

 

I'm currently getting 16mpg hwy with my '03 5.4L Expedition, but only 6-6.5 towing. What I hate more than the low MPG is the loss of range. I'm filling up every 120-140 miles! She's also working hard...sometimes kicks down to 2nd gear on the hwy, just to keep up!

Are you serious, only 8-11 towing? Towing how many lbs? Hardly seems worth the upgrade.

 

Our 6.4's at work get 11mpg empty and on the freeway. I know that gearing and driving styles can help, but I've also read the same issues from other 6.4 guys on here, but if you're getting 17, you must be doing something right. I'd ask lots of questions here about gearing/chassis combos and who gets what for mileage.

 

What sort of terrain are you towing in?

 

mostly flat...but I'd like to tow long distance too. I live in south- western, Ontario (Canada), where it's so flat, you can watch your dog run away for three days! But I towed down to the smokies in 2008, and boy is my Exp working hard! Would like to tow to Utah (4 corners), Montana, Wyoming, etc.

I've spoken to other PS owners that swear they can get 12-16mpg towing, and 20-21mpg hwy...

 

Ernie, I have towed our 28' travel trailer with my wife's '08 5.4 Expedition and know exactly what you are going through. I turn off the O/D and let it sing.

My '08 F250 is stock, 4X4, 3.73 rear diff, factory 18" wheels. My empty mileage in town is driving 20-50 miles/day at 55mph or slower with maybe 10 traffic lights. My empty mileage on interstates (which I have only done a handful of times) really is 17 and change. I live in the south, temps are warm, fuel is not winter blended, rolling hills and flat ground, not much traffic and I set the cruise at 72 and drain the tank, no stopping.

Towing? I drive around 3500-5000 miles each month with a GVW of 15K-18K. Every so often I get to 23K if I need to haul big equipment. My truck weighs around 8K so my trailer weights are generally 5-10K, sometimes up to 15K. My MPG when towing is what I experience most of the time and most all of it is interstate with some rural mixed in, depending on where I need to go. You can get better MPG by driving 65mph on the interstates but I can't do that. I go 72. I get as low as 8 or as high as 10, maybe 11 if I run lots of rural roads where I can't go more than 60 mph for extended periods of time.

 

With overall mixed city/hwy I get between 18 and 20 on a 2000 F350 7.3 w/6speed. This is consistent mileage and has been the case for the last 6 months. Mine is a 2wd extracab so it does weigh less than the 4x4 crew cabs out there. I also run stock tires and have the truck unlifted at stock height. These 2 items will make a significant difference in the mileage you get regardless of the motor you end up with.

 

erniek70, as stated above it depends on what you're looking for.

If you're looking for MPGs the 7.3 is where you need to be. But even the newest 7.3s are getting old at this point and the 5.4L engine you have in your Expedition has more power than the 7.3L engine did. The 7.3 will certainly seem to have an easier time towing it because it makes power at lower RPMs. But when pushed it's simply not going to outperform your current 5.4L unless you are at high altitudes. As old as these engines are getting I wouldn't bet that they'd be any more reliable than a late 6.0 or 6.4L engine.

The 6.0s have an awful reputation. They were plagued by problems throughout the first few years they were made and people have had a bad opinion of them ever since. From what I've seen the later 6.0s have experienced much better reliability than the early ones. I personally wouldn't have a problem owning an '06 or '07 6.0L. These engines have much more power than the 7.3L engines and have the added benefit of a much improved 5-speed transmission. The 5R110 TorqShift transmission has proven to be very reliable and a huge improvement over the old 4R100 that sat behind the older 7.3L engines. It's also worth mentioning that MPGs are significantly worse than the 7.3L PSDs. This is largely blamed on the cooled EGR system that was mandated by the EPA.

The newer 6.4L engines seem to have had a much better start than the 6.0s have. Like any new complex engine it has had it's issues, but most of those issues are relatively minor and less common than the problems that plagued the early 6.0s. This engine is even more complex than the 6.0s as it was designed from the start to meet the EPA's stringent 2007 emissions requirements. Because of this it has a larger EGR system as well as a Diesel Particulate Filter in the exhaust system. Due to these two systems MPGs have suffered greatly. I average between 15-16 MPG empty on the highway and around 10 MPG towing 9,000 lbs. Compared to my '07 5.4L F150 my 6.4L F250 is an enormous improvement when dragging that much weight around. It comfortably holds 65 MPH in overdrive even up some moderate hills. When things get steeper it downshifts once and pulls the hill around 2300 RPM with relative ease. These same hills would have my 5.4L engine down to 2nd gear at 4,000 RPMs!

Take your pick, each engine has it's strengths and drawbacks. I prefer my 6.4L to the other two choices because it's more reliable than the 6.0 and has a better transmission and HP rating than the older 7.3L engines. Whichever you choose will likely bring you years of great service!

 

So, in essence, I'll probably double my towing mileage (from 6 to 11), over the 5.4, regardless of what PS (6.0, 6.4, 7.3)? But, more importantly, the truck is not working so hard! now it's a matter of preference? I agree, the 03-0-5 6.0L has me a little worried, but I haven't seen much about the 06-07. I've also read that noe we have ultra-low sulphur diesel, that the EGR, injector, and turbo issues aren't so bad either. I've read the cleaner diesel does not coke up the engine as much. Is this true? The thasnmission in the 05-07...is it an Allison, or was that not until 08?