I have noticed lately that my 2003 v-6 Explorer is getting very poor gas millage.
I was wondering if anyone could shed some light on might be going on.
Here is the situation. I was getting 18+ miles to the gallon and am now
Only getting 12. I have been filling up at the same station for the last
4 tanks full, current use is for in-town commuting. No towing and not overloaded.
Have been using 87 octane. Also does using 89 or 92 octane increase your miles
Per gallon?

I have noticed lately that my 2003 v-6 Explorer is getting very poor gas millage.
I was wondering if anyone could shed some light on might be going on.
Here is the situation. I was getting 18+ miles to the gallon and am now
only getting 12. I have been filling up at the same station for the last
4 tanks full, current use is for in-town commuting. No towing and not overloaded.
Have been using 87 octane. Also does using 89 or 92 octane increase your miles
per gallon?
Hmm... two very good questions!
First: "mileage may vary"... this is about the time when some fuel companies reintroduce us to their winter blends. Also, you may be running a slightly richer fuel mixture now for a little longer with the cooler weather (I don't know where you live, but many areas are cooler now)

Secondly: Most vehicles are designed to run 87. And most will not benefit from running higher octane fuels, especially in the winter. Higher octane fuels will not increase horsepower or fuel economy!

I hope this helps clear up some myths.

If the gas is E85 you'll take a big performance hit from the old stuff without the ethanol.

If the gas is E85 you'll take a big performance hit from the old stuff without the ethanol.
It's my understanding that the engine needs several modifications to accomidate E85.

Use in flexible-fuel engines
Postal Service truck running on E85 fuel and advertising its use

E-85 ethanol is used in engines modified to accept higher concentrations of ethanol. Such flexible-fuel engines are designed to run on any mixture of gasoline or ethanol with up to 85% ethanol by volume. The primary differences from non-FFVs is the elimination of bare magnesium, aluminum, and rubber parts in the fuel system, the use of fuel pumps capable of operating with electrically conductive (ethanol) instead of non-conducting dielectric (gasoline) fuel, specially-coated wear-resistant engine parts, fuel injection control systems having a wider range of pulse widths (for injecting approximately 40% more fuel), the selection of stainless steel fuel lines (sometimes lined with plastic), the selection of stainless steel fuel tanks in place of terne fuel tanks, and, in some cases, the use of acid-neutralizing motor oil. For vehicles with fuel-tank mounted fuel pumps, additional differences to prevent arcing, as well as flame arrestors positioned in the tank's fill pipe, are also sometimes used.
And it's not better:

E85 gets approximately 25% fewer miles per gallon. In order to save money at the pump the price differentiation between gasoline and e85 would need to exceed 25%, currently E85 is about 5-10% less expensive.
Don't get me wrong! I agree the concept is good!
And, where is it sold? I've never seen it advertised localy?
Frankly, it doesn't seem worth it!

E85 is sold in every station where I live in an attempt to meet smog standards. The mileage hit sucks. Lawnmowers get the higher octane which doesn't seem to be E85.