From what I have been reading, it looks like the "dont use or else" crowd is brain-washed by marketing at its best.
I've been doing A LOT of reading and digging into the info. All modern cars, 1988 on up, can handle ethanol blend just fine. Most cars in the early 90s converted to even better parts for better durability as ethanol blended fuels became much more widely used. This included upgrades to the rubber o-rings used, green in color they should be I think.
In short, any modern car can handle E85 just fine with no adverse short term effects.
But here is what should be know. Tainted E85, that is E85 with water contamination, can create a VERY weak acid (as mentioned above). This weak acid can corrode lines, tanks and injectors as well as the rubber connecting seals. THIS TAKES A LOT OR TAINTED E85 AND MANY TANKS OF IT! Normally you would have to refuel at the same station for years that had bad fuel. With todays standards and the addition of ANTI-CORROSIVE chemicals being added to the E fuels, this is pretty much a mute point.
In short, E85 will not damage your vehicle unless it is tainted. Also, if it is tainted, the gas and ethanol separates and the vehicle can run like crap. Similar to when water gets in regular gas. But since there is always the possibility of tainted gas or the fuel door being left open in the rain, manufacturers use stainless steel or poly tanks, teflon coated lines and injectors. As most here know, almost all Marks have black poly resin tanks - oddly, not all do though.
In addition, since E85 is less powerful at the same volume, injectors are usually upgraded and the car is "tuned" to take into account the excess oxygen to get the best economy and performance out of the fuel.
A flex fuel vehicle will get 10 to 15 percent less economy but should not hinder in performance since the injectors are dumping more fuel in (more fuel being dumped is really what causes the reduction in economy).
So to convert you need to do little. Make sure there is no water in the tank and get a proper tune - however...
I have been doing a lot or driving on pure E85 now and have been watching my economy like a hawk. I drive the same highway route often so I know what milage I get. Here is what I have found and what Torrie is looking for so he can make adjustments to my chip.
On 93 octane I get 28MPG at 65MPH and 24 at 75MPH.
On 85 ethanol I get 20MPG at 65MPH and did not try higher speeds.
In effect, I saved only 30 cents on the last fill. Performance is the same as before but IF there is an effect, it would be a reduction since I felt no increase.
What may need to be done, in the Marks case, is a specific program for E85 and the rest for regular. Mainly I would like to use E85 for long distance trips only. I could not even guess how a stock mark would handle E85.
