Home Forums Gear Hunting Trucks and Four-Wheel Drives F250 Diesel Engine MPG question

We don't really do any tricks - a quality PM service is about it. We run Mobil synthetic with drains at 75,000 miles. Swap filters inbetween. That seems to be the bigger thing - RUN SYNTHETIC. Everything I've seen from where I am now to when I was at Peterbilt - synthetic is the way to go. I saw it in smaller fleets and now in the larger one.

Yes we have failures but combine it with the fact that across 14,000 trucks, we only have to pay a wet service on a unit every 9 months - what we burn down is easily paid for in the savings there. Plus getting a driver in for the service is easier to do when it isn't done every 4 weeks like you would on dino.

We do have a larger than normal fuel filter that Baldwin makes for us special. About 2x the size of normal. Fuel quality isn't the best across the entire country and buying a million gallons a day, you get some not so good stuff. Talking about sediments, not asphaltines or lubricity issues.

Our largest issues seem to be more along the lines of trans failures.

Although - the smaller line of business I work in (within the larger parent organization) is starting to look at rebuilding a portion of the fleet rather than replace. Like everyone they went heavy on the 06,07 years and they are all starting to hit that wall of larger failures/issues at the same time. Rather than replace all of them (we'd rather replace a smaller portion every year -say 20% of the fleet so you have a 5 year turn over) we are kicking the tires on what we'll do.

At the end of the day - we are a large company with several smaller fleets that make up the total. We can and do get to experiment on different things in different regions. We've not found anything that we could attribute to fuel issues that required anything additional to extend the service life, increase MPG (think what .25 better MPG would do for the bottom line across 6 million miles a day) or make our stuff last. We have the same failures, number of failures and severity of failures that we did before USLD.

Andrew,

Thank you for the detailed response. I service my vehicles myself on a regular basis and I use a lot of the same stuff you mention. If it is good enough for your fleet, it should be darn good enough for mine.

What are you running for powers?

We don't do anything that propriatary - what we use is what everyone uses - just that we get them cheaper

Andrew,

It varies from my daily drivers which are 2008 Toyota Sequoia, 2008 Camry Hybrid, 2006 Honda Accord 4 cylinder which I use Mobil 1 and Wix filters across the board. I also change the cabin filters at about 15,000 miles. It is amazing how dirty they get.

I use Shell Rotella dino 15w-40 and Fleetguard filters (oil and air) in my 2000 Dodge Cummins 2500, but I use Amsoil or Royal Purple in the transmission and differentials/transfer case. I have a 1997 Fleetwood Discovery motorhome with a 5.9 liter Cummins which I use Amsoil or Royal Purple in the engine, Transynd in the Allison, and Amsoil/Royal Purple in the differential.

My two stocker race cars (LT1 and a 396/325 hp) I use Wix Racing filters and Valvoline dino with Lucas Zinc additive. On head's up races I use Royal Purple Racing 0w-10 and only 4 quarts. Royal Purple in the Turbo 350 or Turbo 200 and Royal Purple in both 12 bolts.

Curious - why the dino in the engine and Amsoil in the drive train behind it? (Ram) and then Amsoil in the RV engine?

Curious is all as to why the spread on the styles of oil/fluids being used.

The RV will sit for longer periods of time, but it when it is being used it is under much more strain than my truck. I have always used synthetic in the RV and had excellent oil analysis results.

I bought my truck used about 5 years ago. It was more of a work in progress. The truck only had about 72,000 when I got it and I wanted to learn more about how to improve the performance of a diesel with different injector/turbo combos along with modifying the fueling curves.

The first thing I did was to replace the transmission and converter with one from Dave Goerend. I wanted to remove that variable from the equation. I also knew that I would be putting in head studs and changing out the camshaft.

All in all there would be several more oil and filter changes than normal for the time/mileage intervals due to modifications to the engine. I didn't think I would get the full advantage of the synthetic since I would be changing it so often until I got my final combo figured out. At that point I would probably switch to a synthetic and normal oil change intervals.

Funny thing has happened in the process. I have built more motor than the truck can safely handle. Not that the truck is dangerous to drive. It is very smooth and powerful while getting good mileage. The problem is that this combo should be in a long bed dually rather than a Quad Cab short bed single rear wheel truck.

I plan on selling the truck and buying a crew cab dually. I have my eye on a 2004 Ford F350 with the 6.0 and 5 speed automatic. I am aware of the problems of the 6.0, but this particular truck is owned by a friend of mine that has worked most all of the bugs out and takes incredible care of his vehicles. It has 66,000 miles on it and has a nice Transfer Flow tank in the back.

I will drive the truck as is for as long as it gives me good service. If the 6.0 ever gives up the ghost or gives me enough trouble, I will replace it with a very nice 1998 12 valve Cummins that I have sitting in my shop right now. Or I will sell that motor and put a later model Common Rail Cummins in it for the quieter engine.

I hope I answered your question in the prior post about my truck and why it appears unusual that I am using dino in front of synthetics. If you are asking about the various synthetics is more due to availability than anything with the Amsoil vs. Royal Purple. I prefer the Amsoil, but I have a better source for Royal Purple and it is much cheaper for me than Amsoil. I just use the Transynd in my Allison because of the extended drain intervals that Allison approves of with their "in house" product.

I have drifted more to Mobil 1 for the engine oil because I can get it so darn cheap when Wal Mart runs it on sale and it has been giving me the same good oil analysis results that I was getting from Amsoil/Royal Purple. If it has been as good then why spend the extra money. Amsoil, Royal Purple, and Transynd are the only synthetic transmission fluid I have available to me. I can say with certainty that the dino oils I had be using in my daily drivers didn't do as well with the oil analysis that I have been getting out of the Mobil 1, Amsoil, or Royal Purple.

Our dyno results have been surprisingly similar with Valvoline vs. the synthetics in the 5w-20 weights. We have seen the cars pick up about a tenth when we drop out a quart and use the 0w-10 Royal Purple for our heads up races. We have also found that we need to add Zinc to the Valvoline especially for the flat tappet motors. Not so much for the roller cam engines, but the racing synthetics come with the added Zinc in the first place.

Thanks for the explanation. Very interesting. I really appreciate it.

Oldelkhunter,

THANK YOU for starting this thread! Wife and I have been looking at a one size does all vehicle for me to replace my 2000 Ford Explorer and 89 F-250 Gas 460 4x4 p/u. I drive quite a few miles per month as evidenced by the 207,000 miles on the explorer.I must have 4 wheel drive and decent ground clearance to get to many of my mountainous area rural appointments. Add to the equation that I am a might bit bigger than the average joe at 6'3" and 245 lbs plus my absolute aversion to buying a Jap rig and one can see why a Subaru will not work for me. Also needing 4 doors as I almost always have a couple of huting buds along on my adventures. Hoping to buy one rig that will be my daily driver as well as hunting rig and pull the 29 foot camping and hunting trailer. Just read this entire thread as I was about to pull the trigger on a deal to trade in my Explorer and 89 PU on a 2004 F-350 4x4 with a 6.0 liter diesel.

NOW I am thinking of holding off and looking for a slightly older Ford with the 7.3L motor. Am I on the right track? Love the fuel mileage and power of the Dodge Diesels but cannot stomach the body style or that would be my direction. Any input here on the Chev Diesel Quad cab 4x4 P/U's? Is a 7.3L Ford Diesel lots better than the 6.0? Enough better that it is better to get the older and likely higher mileage rig? I am really hoping to get something that will be in the 20+MPG range over the highway, yet still do above requirements. Idea's and suggestions hereby solicited!

Ford made a great diesel engine in the 7.3 but if your in that rig a lot, best be wearing ear-plugs because it will, like the older Cummins diesel, cause you to loose some of your hearing.

The newer diesels are much quiter in that respect....thank GOD!
However, because of the low sulfur fuel, they don't get near the mileage either. In the beginning FORD did have some problems with their new diesel engine but most of that dust has settled down and I have not heard any great complaints about fire coming out the exhaust, like in the beginning.

Cummmins diesels in the 5.9 do get tops in mileage but you must like the rest of the truck or shop elsewhere I suppose. I view a truck like a tool! So body style doesn't way me a whole lot, it is performance and mileage etc. You just remember, you must be doing a whole lot of pulling and running that truck near 60 hours a week to justify the cost of that diesel engine.

My Ford E-350 Superduty gets used between 8 & 10 hours a week, so a diesel is not in my interests or benefit. I can pull 12,000 lbs with that V-10 gas engine and it is as quite as a church mouse on Monday morning. I now (since bigger tires installed) get 13mpg on the highway at 70 mph. I tow 12,000 and get 8.8 to 9.4 mpg. Average life of a V-10 is close to 180,000 miles before major overhaul. Many have gone over 200,000 plus. If you have a diesel truck, you best trade it off before it gets 80,000 miles on the vehicle or you will take a beating and most dealers will not touch one that has over 100,000 miles on the rig. If so they won't give you SQUAT for the truck. You don't have that problem with a gas engine truck!

The FORD 6.0 Diesel was a BUST as far as dependable diesel engines go, if your going to compare it to the 7.3 Ford or 5.9 Cummins engine. One of the reason FORD got on the stick and started all over again from scratch.

I have a very good friend that purchased a 2006 with the 6.0 engine and he has never been happy about his new truck. He would take a beating trying to retrade. So he took that truck to a fellow who is an expert on diesel engines and made some changes, starting with a new exhaust system and added the Bully Dog Box.

He pulls a 32ft trailer loaded with horses, dogs etc. down in the Ozark Mountains where hills are plentiful and steep, such as Hwy 65. He now has most of the Nit-Picking things solved but it cost him lots of heartache and money.

The Chevy diesel is a good one no doubt about that and the plus side is GM has it mounted in front of the best Tranny on the market in that Allison box. Never heard anything bad about the Allison hook up. I don't think you will get in the 20's with mileage but 17 to 18.5 seems the norm from those I know who run them around my area.

Between my dad and I we have had an 1987 (6.9 IDI), 1993 (7.3 IDI) '95 (PSD) and 2000 (PSD). They all got 16mpg +/- hwy. We always heard from everyone that we should be getting 20, but in reality never got close. I think its an internet rumor.

I've only owned the 7.3 in Excursions, one a 2000 model and the other the 02 I presently own. My driving habits with both being the same, 2000 rpm is a 'never exceed' rpm for economy's sake. I could consistently knock down 20 mpg on the highway with the 2000 model, hand computed, not what I saw on the overhead. The '02 I presently own has never achieved better than 18.1, and the loss is directly attributable to the fact that it has 285's on it in comparison to the stock 265's the 2000 had. As always, bigger rubber is a penalty.
Both trucks towed in the 12-14 mpg range depending on wind and terrain; 8000# twin-engine boat. Both trucks had the same fuel mods and ran the same Superchips programmer.
Jim

Not just to start an argument, but what you've said is not the same mpg as what alot more people have said they got...including me. Your figures sound like you limited yourself to 4.10 rearends and aren't telling us that. Maybe it's something else, but if I took your trucks and drove them, either I'd have gotten better mileage than you did, or there's a mechanical reason why, unless you have a knack for buying lemons, drive in a way that uses more fuel than most, or your trucks were set up to not be able to get the same mileage as I know they can get.
Your statement, taken at face value, is more like an internet rumor than it is a presentation of factors that would show why it is true...or not true. So, instead of just throwing out a blanket statement, why not tell us more about your trucks and how they were driven?
Or maybe "but in reality never got close" means you "only" got 19.9 mpg.

son-in-laws 99 F350 powerstroke gets 17mpg highway at best . local driving on township and county roads he gets 14mpg .
he doesn't have 4.10 rears


I've talked to many powerstroke owners that never see 20 mpg .

While I don't doubt what you are getting because the best I have now gotten with my '06 psd is 18+ mpg (empty, slow and 3.73s), there's a guy in this thread claiming 32mpg. What do we do now?
My older trucks of other manufacturers' got better mpg than my '06.
Alot of mileage differences boil down to terrain, speed, load, gears, air filters being clean, wind and honesty---plus the ability to accurately calculate mileage. These discussions will always be around, because of the apples-to-oranges tests.

I have an 01 4x4 F-250 with the 7.3 and 285's, Mobil 1 gear dope in both ends and Rotell T 5-40 synthetic in the motor. I also use a DP Tuner programer with the 80 hp 'econo tune' and the 60 hp 'tow tune', it's all push button so I can easily change from one to the other. I average 16-19 in town and on the road, the very best I've seen is 19.8 and that was ALL highway keeping it below 2000. The last time I filled up it calculated 18.1mpg. When pulling our toy hauler I usually average around 12 mpg. All milage is 'hand calculated' and NOT from the 'lie-o-meter' on the overhead, it usually shows 20-25...I only wish!!

Just read a review in one of the car mags, maybe MotorTrend and they were getting 15-18 mpg with the new Ford Super Duty. Better than the Dodge they were comparing with, FWIW