Ethanol Destroys Engines
Our current pump fuel is E10, a mixture of 90% gasoline and 10% ethanol. Unless you are one of the handfuls of riders in this country that has access to pure gasoline (see pure-gas.org), it's what you put in your motorcycles, cars, boats and small engines.
Corn produces 95% of the ethanol used for motor fuel. But, unlike MTBE (methyl tertiary butyl ether), the carcinogenic oxygenate mandated as our previous godsent fuel additive, ethanol does not mix easily with gasoline until it has been "dried" to 99.9% pure (virtually all the water removed). But as fuel ethanol is the very same chemical that has provided recreational benefits to humankind for at least 9,000 years, water is a key ingredient in its creation.
Just as you would do to make beverage alcohols, the corn is typically ground to a fine powder and mixed with water to create a mash, which is then treated with enzymes that convert starch to sugar and then seeded with yeast to ferment. Unfortunately, the yeast dies when the alcohol reaches about 20% of the brew, leaving a higher proof to require distillation (heating the mash to boil off the lighter alcohol into a condenser, a process simple enough to be carried out in the backwoods.)
Why should you care how much ethanol is in your gas? A chemistry lesson will explain: Distilled spirits can reach 190+ proof, plenty to create psychoactive entertainment, but 96.5% pure alcohol still contains 3.5% water, which is why it is called hydrous alcohol. Now, hydrous alcohol was actually used as a motor fuel until about 1930, although Prohibition made it problematic after 1920, and Henry Ford himself designed his earliest cars to run on either gasoline or alcohol. But, as mentioned, hydrous alcohol won't mix with gasoline. So, to achieve the near-perfect purity needed (anhydrous alcohol), additional treatments in the form of high-pressure distillation and filtration -- like passing the liquid through zeolites (naturally occurring mineral lattice structures that act as a molecular sieve) will eliminate nearly all the water.
However, this "drying" does not change alcohol's affinity for water. Alcohols of all kinds (like glycol brake fluid) are hygroscopic, meaning they pull water from the air. This fact makes it impossible for alcohol producers to use the vast network of oil pipelines for cheap transportation, as the ethanol would suck water out of the lines (oil and water, of course, don't mix). Mixing the ethanol and gasoline is therefore done closer to the gas pump, and incorrect mixtures (much higher than 10%) are often found to be the cause of fuel system problems. Anyone advised that an expensive fuel system repair is needed would be smart to have the fuel's ethanol concentration tested. Test kits are cheap, starting about $25 on the internet.
There are two unintended consequences to gasoline/alcohol blends. One is phase separation, which is when the alcohol in the fuel as drawn in enough atmospheric moisture that it drops out of solution with the gasoline to rest at the bottom of the fuel system. Corrosion is the other, caused by both chemical and electrical effects. It not only increases the fuel's electrical conductivity to speed galvanic corrosion, but by itself, alcohol is a potent solvent; corroding metal, eating plastics and hardening rubber. Aluminum oxide, which looks like white rust, will form at the bottom of float bowls and other aluminum fuel system components, where it risks clogging tiny fuel passages and being drawn into the intake system. And recall that aluminum oxide is the same sharp abrasive used on sandpaper. Boaters especially have had major problems as fiberglass fuel tanks, often built into boats during the construction phase, break down and leak in contact with ethanol, which then suspends various polymers in the fuel to create engine deposits. Older motorcycles with fiberglass gas-tanks will have the same issues.
Fire hazards develop when high pressure fuel rails corrode and leak, rubber fuel hoses become brittle and crack from vibration and the plastic gas-tanks on some new machines soften and swell up to leak at fittings. Ethanol resistant fuel hose is now available to replace the old type, and any machines built before 1999 should have them all changed as a precaution. But not all the vulnerable parts, gaskets or seals you need may be available.
Phase separation will also allow the water/ethanol mix to form a milky slime that adheres to the walls of the fuel system. When the engine is turned off and the system has a chance to dry out, this slime will harden to break into insoluble amber pieces that clog fuel flow. This crud may also contribute to the extraordinary deposits sometimes found on the intake valves that also restrict flow. Temperature changes and humidity accelerate the onset of phase separation, and in the worst case can create problems with fresh E10 in just a matter of weeks.
Engines that see constant use will suffer less problems, but many engines are used infrequently, as in sporting or landscape equipment. These engines are also less likely to have sealed fuel systems that prevent unnecessary air from entering their gas-tanks.
Two-stroke engines experience two major problems: In addition to clogged fuel systems from phase separation, corrosion and rusting, alcohol breaks down the effective lubrication of fuel/oil mixtures, leading to seizures.
What can you do? Fuel tanks can be stores 95% full to reduce the presence of atmospheric moisture, and fuel stabilizer type additives can help reduce corrosive effects but cannot reverse or even delay the onset of fuel separation. Small engine manufacturers are now starting to sell quart bottles of pure gasoline premix to eliminate complaints, and custom fuel suppliers like VP Racing now sell cans of straight petroleum super-premium to racers and owners of vintage vehicles to prevent problems. Neither is inexpensive.
These problems are well-known, and it's no surprise that the FAA bans the use of ethanol/gasoline blends in aircraft, but not all states require that E10 gas pumps must be labeled. The car and motorcycle OEMs that allow E10 all recommend discontinuing its use if problems develop and some will also refuse to cover any fuel system problems under warranty.
It's far from an easy solution, but avoiding ethanol is the only sure cure.