[dwtaylorpdx]

My jeep weirdness stuff...

The Jeep ecu does not adjust well to E10. (I've owned my Wrangler since 1994 bought it new.) Oregon used to switch to E10 in the winter and to regular in the summer. It was absolutely repeatable, I'd lose 4 MPG highway in the fall and get it back in the spring.

Then they started keeping the Portland Metro on E10 year round, I regularly drive to the eastern half of the state in the summer. 120 miles of virtually flat freeway I'd have a tank of the city gas and get 15 mpg going east, then fill up to come home and get 19 to 20 coming west to home (Depending on the crazy headwind we get in the Columbia gorge.) Its of note that the Eastbound direction I had a tailwind 90% of the time. (Standard prevailing wind in this area.)

Now its all E10 and my mileage stays in the 15 to 16 MPG range...

There are some adjustable crank position sensors that allow you to mechanically tweak the timing (The jeep does not use the distributor for ignition timing on most newer models.) It assumes a static timing point off the cps and adjusts the timing electronically. The ethanol cools the mixture and raises the octane unless the vendor used the ethanol to bring the octane up in the first place. The E10 rating is a minimum, its legal for them to be up to 15% without telling you in most states.

My jeep is also really sensitive to the Air filter, I run the stock air-box, and have been fiddling with switching back and forth between a K&N and a Standard Fram air filter. I've noticed power and mileage drop off pretty quick with the filter at what I would think is its half life. A quick shot of air backward through it from my shop vac cleans it right out.

I have a manual transmission but I've heard anecdotal stories that the Grands and the Wranglers with autos get better mileage with high performance fluid in them ...

I run redline or amsoil in the diffs and I use the stuff they recommend for Dana Axles, and ignore the MOPAR info because they spec too heavy of fluids in most gear boxes.
The AX5 manual behind the wrangler 4 cyl lasts way longer on lighter oil. (Its a known crap gearbox so YMMV) Funny thing is the book says use 70w90 synthetic but the viscosity of the special Mopar branded AX5 transmission fluid is the same as 20w50... At least through my viscosity gauge it is.... And when I got the trans rebuilt the builder said use 20w50 synthetic motor oil... Has worked for 120K now.. the same trans is used in some 80's and 90's Toyotas and they also spec a lighter lube from the factory...

Just some sortof tried and true data from my point of view...
Dave