[quote name='Harvey' date='Feb 24 2006, 01:32 PM']It's unconfirmed but I've heard that the ethanol mixes are not recommended in the older cars because it's hard on the rubber parts in the system...particularly if vehicles sit much. I'm staying away from ethanol until this is proven...
Just me.
Harvey
[right][post="16508"]<{POST_SNAPBACK}>[/post][/right][/quote]
Harvey,
You may be getting mixed up between ethanol and methanol. Years ago, the oil companies began offering a methanol blend of gasoline, and quickly learned that the methanol attacked anything that was rubber in the system. I believe that the majors bought a lot of new engine parts as a fallout of that mess.
Ethanol, though, is a completely different animal, and I am not aware of any compatibility problems of ethanol with any of the materials located in your fuel system. Since ethanol provides an octane boost, you will see higher octane blends, where local laws allow. In Chicago, we can get 93 octane blended gasoline while Southern California disallows that and has a max of either 92 or 92.5 (sorry I don't remember the exact octane limit there).
If there is a problem with ethanol, it has to do with water. Ethanol is hydroscopic, which means that it has an affinity to absorb water. So, if you pick up some water in your fuel system (which can happen if the station operators aren't diligent about pumping water out of their underground tanks), the ethanol will absorb the water from the system. This is OK until the volume of water reaches a point where it supersaturates the ethanol. When ethanol absorbs more water than possible, you get what we call "phase separation", which means that suddenly, the ethanol/water mixture will separate itself from the gasoline in your system. This separation has to very bad outcomes. First, since ethanol provides an octane boost, the base gasoline is blended to a lower octane than required.......and the addition of the ethanol brings the octane up to its limit. So, when ethanol separates from gasoline...........the gasoline will drop to an octane somewhere in the 70's or 80's. Our high compression engines don't really run well (if at all) on 80 octane fuel!
The second negative of phase separation is that you end up with a phase that is an ethanol/water mixture. If this mixture gets into your engine...........you'll find that the engine will not run at all!
When ethanol first became available, as mandated by law, my company (ExxonMobil) paid for a lot of towing and major engine work as cars failed to even get out of our stations without stalling, until we became knowledgeable about the phenomena of phase separation. Since then, we are diligent in monitoring water in our tanks........and the issue has essentially disappeared.
Sorry for the long message. Incidentally, one positive of ethanol is that you no longer need to use any of the aftermarket chemicals to prevent fuel system freezeup at low temperatures due to water in the system. So, you can save your money and not buy any of the STP products.
