CDX825
filtration nut
Your mileage may be showing low because of tire size. Any idea how accurate the speedo is?
Fuel Mileage
- Thread starter Danoflapper
- Start date
I have a pretty much stock 86 Work truck with 4.10 gears and C6, but last tank I got 17 mpg highway but unloaded. Every tank gets ATF, a can of Isopropyl, and either PowerService or an old Iso bottle loaded with a concoction I mix together to clean things and spice up the mix. I'm ok with the mileage with this setup.
Last time I checked, which was a trip from Pittsburgh PA to Gastonia NC and back, I averaged a bit over 18.5mpg. That was on 285-75/16s. I'm running 235-85/16s now, so I'm hoping to get a little better. Going from a 32.8" tire (technically) to a 31.7" tire might hurt a little, but the reduction in rolling resistance should hopefully make up for it.
Csgod0
Registered User
wow I'm missing somethign here. I get maybe 9mpg on 88 7.3 with 4.10 C6. 17 unloaded? I might have something not right with my truck then. I haven't checked the tire size yet, but its a dually, and I might be restricted with how large I can go.
Brianedwardss
Registered User
Lately Ive been getting 13! So you're not alone
I find that with my little mix of additives which include some ATF, I still get 16-18 mpg even loaded. My tires are the same I run on all my 16" tired trucks - 265-75-16 with proper inflation. The 6.9 is a wonderful engine, I wish I had gears in the 3's for some better mileage, but I still tow on the farm, so 4.10's it still is and will be. Maybe an over drive someday...
Csgod0
Registered User
i can see that my tires are massive undersized compared to everyone elses. I have 215/85/16s, when I should problably push my way towards 265-285s. Does anyone offhand know how large of Tire could be swapped onto a dually before needing spacers?
Goofyexponent
Mentally Unstable..
My truck weighs in at about the same as yours. I have 245/75R16's..but they are really aggressive tread (mud terrains) and I am seeing between 19 and 21 MPG. I usually drive 55 - 60 MPH on the highways, and just drive it like an 85 year old woman would drive a Prius Hybrid.
I find if I use the cruise, act like there is an egg between my foot and the go pedal and non't jackrabbit light to light, I get better milage than some newer full size 4x4's!!
I find if I use the cruise, act like there is an egg between my foot and the go pedal and non't jackrabbit light to light, I get better milage than some newer full size 4x4's!!
to get a good reading you need to use something a little more accurate then your speedo. i use my garmin gps to get the mileage and hand divide from there. i have had a leak in my fuel system that i found this weekend and have been consistently in the 17's an drive like i stole it.
mj05
Full Access Member
In a previous thread someone thought that 255/85 tires are the way to go... they're 33 inches tall but not as wide as 33's or 285/65's. They should roll nicer over bumps than the smaller diameter tires too. You get more height and less rolling resistance.
Danoflapper
Registered User
I'm going to fill up tomorrow, have to see how I do this time. I haven't bothered to find my mileage since the first time.
FordGuy100
Registered User
Drove from Oregon to Texas doing mostly 65-70mph....through some ok grades (I-5 south, I-40 over through Flagstaff). Loaded down with about 1000-1500pounds of stuff....got right at 17mpg.
1994IDI
Registered User
Yes, he is putting ATF in the diesel to lubricate the fuel system.
QUOTE: On my 93 F250 4X4 with the ZF5 and 4.10's I'm getting 15 mpg on the hwy running 70-75 MPH.
-x2
I can see 16.5 if it's all highway and I don't go over 65 with the truck in my sig. But my mileage is more realisticall 15.5 hightway, 12 city.
I don't think your mileage sounds to far off with an automatic tranny and the truck loaded. It seems like taller tires and earlier shifts would certainly be helpful though.
Just my 2 cents. Hope it helps and good luck.
QUOTE: On my 93 F250 4X4 with the ZF5 and 4.10's I'm getting 15 mpg on the hwy running 70-75 MPH.
-x2
I can see 16.5 if it's all highway and I don't go over 65 with the truck in my sig. But my mileage is more realisticall 15.5 hightway, 12 city.
I don't think your mileage sounds to far off with an automatic tranny and the truck loaded. It seems like taller tires and earlier shifts would certainly be helpful though.
Just my 2 cents. Hope it helps and good luck.
Csgod0
Registered User
I'm going to get my fuel system examined by a diesel repair shop just to make sure everything is right. new tires are out of the question right now, and I'm trying not to assassinate my wallet and buy the GV from the marketplace, even though i could use it so much. I have little repairs and all kinds of financial wreckage thats in my way.
