My '91 2.5 E code w/5 speed averages 27.5-28 mpg. There are times it'll get 29-29.5 mpg. I don't have the luxury of getting ethanol free gas around where I live; so I'll run Stabil every so often in the tank. My average for the first year or two that I've owned the truck was 27/5.....before I started running Stabil in the gas.....then it jumped up a little after using it. I've got a 20 gallon tank and will top it off until it fills up the filler neck! LOL! I know my gas mileage will be right around 28 if I've gotten 350 miles on the odometer by the time it's down to half a tank. I never changed the ignition module or coil; but do keep up with plugs and oil changes. I'm running 2 quarts of 20/50 Valvoline VR1 Racing oil (with zinc) along with 1 and 1/2 quarts of regular 10/30 Valvoline. The engines seems to run a little better with the VR1 oil....probably because the damn stuff seems to stick to the internal parts better. My friend uses it in his blown 392 and 426 Hemi engines; and after tearing down the engines he says he can grab ahold of the crank and that shit is still on there good and sticky! LOL!

 

Damn, my '92 A code Duke 5 speed/ 3.42 only gets 23 (barely). It even has a header and big exhaust...

 

I would think the rear gear, header and exhaust is hurting the MPG more than helping......

 

mine runs alot smoother on 100% gasoline.

 

i get high 20s, if i kept it around 70 instead of 80 i could probably get 30 ish with some fresh plugs

 

I just took a trip yesterday evening to my step mother's funeral........3 hour trip one way. I had made sure to top the tank off to the point of filling up the filler neck the night before. I added 4 oz of Stabil since I have a 20 gallon tank. On the way home I stopped to top the tank off again........filled it up to the filler neck again so I knew I had the same amount of gas back in it. It took 10.08 gallons and I had put 310 miles on the truck. I was a little surprised to see that the gas mileage went up to 30.75 on this trip since it's usually around 28. I know my mileage is a hair better when I run the Stabil; but do not know how much of the increase in gas mileage was due to changing the worn out cap, rotor, and plug wires. I had swapped the plugs out around 6 months ago so I didn't both changing them again. Now, if I could only get ethanol free gas around here I might be able to average 30-31 all the time! LOL!

 

I've never used Stabil in anything I was driving regularly, so I don't know much about using it, but does the extra cost of buying a bottle of Stabil make the extra mpg worth it? Just curious about the economics.

Also, I've heard Seafoam works wonders. Anybody running Seafoam in their Dukes?

 

I guess it depends on which Stabil you buy (there's a more concentrated version that's blue in color).......and how often you use it. I think it was around $7-$8.00 for the bottle of red Stabil. I have a 20 gallon tank; so I think it called for 4 oz......1 oz treats 5 gallons if you are running the gas through the vehicle on a daily basis......double that for storing that much gas.......IF I am remembering correctly. Anyway, if you can treat enough gas and gain more in mileage then what the Stabil cost you are doing good! LOL! I haven't sat down and really crunched the numbers; but think it's about a wash. The reason I occassionally do it is to help the truck run a little better, kill the ill effects of the ethanol, and pull any moisture out of the tank.