OK, I know it isn't a Prius, but should the average mileage on the overhead display be going down as more miles get put on my '07 1500 Mega Cab (Hemi w/ 4x4 & 4.10 rear)? Has about 7,000 miles on it. When I first got it I was in the 12's pretty consistently, even maxing in 13-ish territory for a bit. Now it seems that I can't get it over 11.5. I tried "bumping up" to 89 gas, although I know it shouldn't do anything for mileage, but the first tank and a half of 89 didn't seem to help much. Is there anything I can check, or have the dealer check? It seems to have started once the 6k service was done at the dealer, but I have no leaks, no wobble, etc. and I can't imagine how an oil change & tire rotation could affect this.

Sean

 

hmm... well the winter blend gas may be a part of it... also you SHOULD run 89 octane gas... read the manual... have driving habits changed? also the overhead display lies.. check it by hand...

 

I read the manual, which also says 87 is acceptable, and since it is less $$ I figured I would try it, and it seemed to run fine. It is probably just for the compensation of the O2 sensors anyway, since they give such a long warranty higher octane means they don't burn out as quick.

Driving habits haven't changed too much, not driving as much though (working from home more often), so it sits a little more than usual, could there be condensation building up? Winter here in CT hasn't been too bad road-wise, so I haven't had to leave it in 4x4 for extended periods of time.

Sean

 

The overhead puter just gives you the average mpg...try resetting it on the freeway or during city driving when you're not in a hurry. And like td mention, driving habits play a huge role in mpg.

 

What? You told you that? Octane is just the fuels resistance to igniting....the higher the octane the less chance of detonation in engines withhigher compression, advanced timing, running lean...etc. If dodge really wanted to extend the o2's life because of the warranty they'd probably recommend a service interval for them...since cleaning them with non-residue electrical cleaner can extend their life.

 

Bumping up to 89 shouldn't do anything for mileage? What!!! I get a minimum of 3 mpg better fuel economy with 93 octane gas over 87 octane and my best mpg tank is routinely the one I put octane boost/fuelinjector cleanerin every 1500 miles or so.
You paid how much for that Megacab? Spend the extra friggin' .10 on the gas...

 

yea i still think its a good idea to run the nicer gas... i run my tuner on 93 all the time and i get the best gas mileage and performance that way...

 

Toastedote,

Threereasons for your decrease

(1) Winter blend of gas
(2) The outside temp, the lower, the richer the mixturetill you exceed 160 degrees
(3)You lose about .6 psi for every 10 degree drop, increasing rolling resistence. Check your tires.

But aleast we get snow in the northeast

 

Maybe this is just in my manual, but it does say for 5.7's it's recommended to use 89 octane...

 

it says recomended 87 to 89 and not to use premium. so regular is a recomended fuel and 93 is not