I just purchased 2000 F350 DRW Super Duty 7.3 with a 4R100. I must say that I am not impressed with this transmission and was looking for a ZF6 but just could not find a reasonable milage truck. The mpg seems poor compared to my 7.3 IDI in a '92 F250 at about 13 highway. the truck is very clean and otherwise nice but 13? I want to blame the 4R100 as I have avoided auto trans in all vehicles over the last 4 decades. It has a Banks turbo. Any thoughts?

 

Back in 2000 my new F350 CC 4x4 dually would get 14 tops. I would say you are within range. Towing was around 7 or so.

 

OK, that driving was empty and all highway NOT romping on it. It does have good power. We will see what happens when I put a 4K load on it.

 

My 2000 250 with the same 7.3 and 4r100 is currently getting about 13 most of the time. If I put a really big load on it, it will drop to 10, maybe 11. If I am willing to drive it 45 mph for extended periods, I can see 20+ mpg. I was forced to do that coming across a couple of states years ago during an ice storm. Normal trip that took 6 hours, was 13 hours that day. You're right in line with what a heavy working vehicle will get. There's nothing wrong with the 4r100. It's a good tranny that can take a huge chit load of abuse. Mine's had 375k miles of pretty hard running and is still working fine. Yes, I've changed the fluid and I recently had to go in and tighten the 3 feed bolts are loosening up on all the 4r100's. I've got no complaints with it and it doesn't own me a single penny. it can blow up on the way home tonight. I'll rebuild it next week and keep driving it.

 

No way, my dad has a 2000 7.3 crew cab short bed with leer brewing addition cap. 3.73 gears with 2 inch level leaf springs and 285/75r16 mickey Thompson MTZ tires and he gets a steady 16.5 mpg around town driving. If he highways a lot the truck easily gets 20mpg maybe a tad more and that's with 230k on he motor. All done by him

 

Start off with a new Motorcraft fuel filter, check/replace the exhaust back pressure sensor and clean the tube out. Also make sure the air filter is clean and not one of the junk k&n types. Make sure all the intercooler boots are tight and not leaking, also check the turbo impeller for signs of wear or damage. Just becasue a truck is "clean" doesnt mean it was taken care of properly or beat to death then put out dry

almost forgot make sure the parking brake isnt dragging or the calipers aren't sticking. Check front unit bearings also

 

I'm with SDScaler. You now have a baseline for MPG without really knowing the condition of your new-to-you truck. So, perform the requisite service maintenance on all fluids, filters, tubes etc. and do an inspection/tightening up, cleaning on the rest of the bits. It certainly won't hrt ... and it should help. If nothing else, you'll get familiar with your new vehicle.

 

please delete this reply

 

I think the 3.73 gears have way more to do with your dad's excellent mileage than anything else. The OP has a dually, I'd guess 4.56 gears for towing.

 

 

7.3 duallys have a 4.10 or sometimes a 3.73 gear ratio I believe. My 1999 f250 7.3, extended cab short bed, 4x4 with 3.73 gears and a 4r100, leveled on 305/70/16 (about a 33x12 tire) gets 15-15.5 in town, and 19-20 on the highway. Although that's hand calculated and I haven't accounted for trip odometer error due to the bigger tires. So it's actually probably a little better than what I get. Depends how cold it is outside too. If the EBPV is kickin, that'll suck more fuel than when it's not kickin. And after 3.5 years of driving mine, I've noticed that I get a tad better mpg when it's warmer out.

 

 

Is that mileage hand calculated from full tank to full tank or from the overhead display?
I regularly get 16+mpg combined regular driving & 11-12 pulling a 36ft 5th wheel .

 

When I bought my signature truck in '03 with 59k miles on it I was getting about 14.3 mpg. I've gotten as high as 15, and lately have been getting 13.5. I just found where a front brake caliper has been hanging up, so I expect it to increase soon as I get it back on the road.