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  Topic Review (Newest First)
03-07-2019 04:25 AM
michealdevine oh thanks a lot! i figured that might be the case but was just checking to see if anything could have been the problem.
01-22-2019 01:05 PM
kotagirl72 Running 33's with 3.73 GR and I'm getting 19 MPG speedometer is almost 10 mph off so I run about 52 which means I'm running close to 60 MPH. Around here people seem to run about 70-75 so I hold everyone up. lol
01-04-2018 06:31 PM
thejeepster99
Gas Milage

im running 35s on 373 gears and dont know i my jeeps a freak but im getting 17-18 mpg and im happy with that it euns great but im going up to 36in swampers so im sure it will go down a little was thinkin about goin up to 488s just dont have the cash for that as of now....
09-29-2017 02:09 PM
Clarence_Beeks 12.5 MPG all around avg, for a 2006 TJ, auto. 4" lift and 33" (KO2's). 53K miles on her too.
08-01-2017 04:35 PM
40gearhead
06-14-2017 02:09 PM
Donuts31 24 mpg on highway, 15 mpg towing ATV trailer, 18 mpg towing snowmobile trailer in winter. 2007 WK CRD.
06-06-2017 04:03 PM
AMcMartin82 With a 5.7L V8 GC, i get around 16L/100km in the city during rush hour. But surprisingly, it drops REALLY low on the highway. On the highway i hover around 8L/100km, which is insane because my Subaru WRX would get 7L/100km at best and this GC is a heck of a lot bigger and heavier. We haven't taken an official road trip with it yet though, so i'll be interested to see how far i can get on a single tank of fuel.
05-08-2017 08:10 PM
bszymborski Interesting
02-07-2017 04:07 PM
Charley3
Quote:
Originally Posted by 97TJNamedJill View Post
my 97' TJ 4.0 gets around 17mpg city and 18.5 combined but I dont really do a lot of highway driving. Ever since I put the stainless exhaust on and used marvel mystery oil over time the mileage improved. I have a 2.5'' lift with 31s and 3.07 gears. Very rarely do I use 5th gear. If Im going 70+ I can use 5th but I do around 40 in 3rd gear at around 1,600 rpm. I wonder if 17 mpg city is good for my setup.
I think you're doing well.

===

Quote:
Originally Posted by JeepGirlPA View Post
Gas mileage is also affected in winter by the additives put in gasoline to keep it from drawing in water and freezing. I usually put in 1/4 bottle isoheet when I top up and it brings back the fuel mileage a little.
It's good to learn of Isoheet. I might try that.

===

Re Marvel Mystery oil and other methods of cleaning topend of engine...

My mechanic used a professional product-system-machine to clean my engine's topend. It's called Motorvac. Same concept as Seafoam, but I think Motorvac is more effective. Marvel Mystery oil added to gas tank is an old school way to clean topend of engine. I learned of using MMO to clean top-end when I was in auto-shop in school 30+ years ago. My grandpa used it 60+ years ago. MMO is old school, but it still works today. If I was going to use a DIY method of cleaning top-end, I'd use Marvel Mystery oil because I think it's safer than Seafoam. However, I think Motorvac is most effective and worth the cost ($125) that I paid my mechanic.

===

My gas mileage is pretty good for a Jeep 4 liter engine with auto tranny, 1.5" lift, 30x9.5R15 AT tires, and 200 lbs skidplates. Driving at 60 mph on level highway I get 25 mpg on a good day in Summer, or 23 mpg on a bad day. It averages 24 mpg in Summer. I haven't tested my Winter gas mileage. So I don't know what Winter mpg is, but I think it's OK because I don't have to fill up very often.

Here is a thread I made that explains things I did to improve gas mileage of my 99 Cherokee XJ. https://www.jeepforum.com/forum/f11/m...5-ats-1551782/
02-07-2017 03:54 PM
Charley3
Quote:
Originally Posted by barkle View Post
"marvel mystery oil"? what, exactly, is in that stuff?
It's a thin-weight super HIGH detergent oil (almost like a solvent) that lubricates a little and cleans alot. If you put a little in gas it cleans your top-end. If you put a little in your motor oil it cleans bottom-end.

However, be careful cleaning bottom-end because if a large chunk of carbon comes loose in your motor oil, it can damage bearings. If you use it in bottom-end, make sure you have a new oil filter when you add MMO and then change filter again after 100 miles in case any chunks of carbon got into oil.

My preferred way to clean bottom end is to use synthetic motor oil. All brands of synthetic motor oil have high detergent.
02-04-2017 06:17 PM
97TJNamedJill It's an oil additive that's been around for decades, it really works I put it in all my dirt bikes too.
02-03-2017 11:36 AM
barkle "marvel mystery oil"? what, exactly, is in that stuff?
08-30-2016 09:38 PM
97TJNamedJill my 97' TJ 4.0 gets around 17mpg city and 18.5 combined but I dont really do a lot of highway driving. Ever since I put the stainless exhaust on and used marvel mystery oil over time the mileage improved. I have a 2.5'' lift with 31s and 3.07 gears. Very rarely do I use 5th gear. If Im going 70+ I can use 5th but I do around 40 in 3rd gear at around 1,600 rpm. I wonder if 17 mpg city is good for my setup.
08-22-2016 08:48 AM
JeepGirlPA Gas mileage is also affected in winter by the additives put in gasoline to keep it from drawing in water and freezing. I usually put in 1/4 bottle isoheet when I top up and it brings back the fuel mileage a little.
02-03-2016 10:41 AM
erndizz yeah i averag elike 15 depends on my driving
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