Important E10 Ethanol Fuel Precaution: Ethanol alcohol fuel blends expire in 90 days; When exposed to excessive water, they may expire even sooner.
Studies have shown that after only 100 days, alcohol fuels absorb enough moisture to phase separate. Octane will drop when fuel phases separates...
If you are not monitoring or "testing" your gas for alcohol and water content, we recommend replacement of gas in your fuel tank at least every 2-4 weeks to avoid alcohol and water related engine problems.
Alcohol blend fuels become contaminated by water dilution (phase separation) very quickly. When this occurs, gasoline octane of the fuel in the tank may frop as much as 3 points...
Protect your engines from purchase of lean or diluted fuel (low octane)...
Simple, easy, accurate. Mix small amounts water and fuel from pump or tank into the test tube included, shake to mix the contents. Wait a few minutes until settled. An increase in the amount of water on the gauge indicates that alcohol is present in the fuel. The gauge will also indicate the percentage of alcohol. View testing procedure and instructions.
Fuel that tests greater than 10% alcohol is "bad" and should not be used in conventional engines. Some motors (airplanes and certain marine engines) can NOT use fuel that contains alcohol. Check with the motor manufacturer for fuel recommendations.
By 2008, most gasoline stations have switched to ethanol-blended fuels, replacing MTBE, for oxygenating fuel. The gas pumps are not required to disclose that gasoline contains ethanol alcohol in almost all states!
An Alcohol Fuel Test Kit will give you the data you need to keep engines safe with E10 gasoline.
PURE ethanol has a very high octane, about 114, but many mistakenly believe that E10 conventional gas sold has "extra octane" then stated at gas pump.
Regarding octane and E10 gas, buying sub-octane gas is more common, then "extra" octane.
Since ethanol is considered an octane enhancing additive, if/when E10 sold has less than exactly 10%, the result will be sub-octane gas (less than number stated at the pump), AND,
When E10 gas phase-separates (high octane ethanol drops to the bottom of the tank with water), the upper tank layer octane typically drops 2.5 points. E.G. 87 octane gas purchased now becomes sub-octane 84.5 gasoline. E10 gas is available in all grades, including regular-87, premium-91, racing-014, etc.
Testing a fuel sample from tank bottom for alcohol percent will confirm gas contaminated with water, and is not safe for use. After phase-separation upper tank layer typically drops from 10% ethanol to 0-2%, and lower tank layer typically test 60-95 percent alcohol (can/will damage engine).
-------------------------MORE INFORMATION Octane + E10 Fuels----------------------------
An octane number is a measure of gasoline's ability to resist pre-ignition, also known as "knocking" or "pinging".
Octane is a rating, similar to a ratio of measurement, not a substance chemical or product you can add to gas.
All gas types are available at different octane measurements - E.G. 87, 89, 91, 93, 110. Currently, even racing fuels, may have ethanol added. Aircraft and diesel fuel should never contain ethanol alcohol.
Determining octane measurements involves a complex methodology.
Portable octane analyzers (testing equipment) are available, but their use by the public is limited due to the high cost, typically between $8,000 to $14,000.
Gas purifying equipment that will remove water and alcohol from gasoline is also available, but like octane analyzers their high price tag often limits use by the general public.
While it's true that pure ethanol has a higher octane number, (reason ethanol is ingredient used most often in octane enhancing gas additive products), E10 gas does not have an octane higher than conventional gasoline. (Choose grade of fuel at pump for octane you prefer).
When fuel absorbs moisture the octane reading can dramatically decrease.
Fuel that has experienced water contamination (W/C) and phase separation (P/S) will decrease about 3 octane points...Many refer to this as "lean fuel" or "diluted fuel".
Many people choose to purchase a higher level octane blend when purchasing E10 fuel - to prevent octane from reaching a dangerously low level if fuel contaminates with water.
Always purchase high quality fuel, test for water and alcohol before purchase, follow necessary precautions, and refill tank often.
Replacing fuel in your tank every 1-2 weeks will usually maintain the octane rating by limiting the occurence water absorption into gas tank.
Running on gas with the appropriate octane rating will offer best performance and increase the useful life of the engine.
To maintain the octane rating listed at time of purchase, following simple ethanol precautions to protect fuel quality.
E10 Tips + Precautions listed here, (http://www.fuel-testers.com/ethanol_engine_precautions.html) should be all you need to do to assure engine is running on stable, high quality fuel with an appropriate octane level, recommended by your engine manufacturer.
E10 gas (10% ethanol) that has phase separated from water absorption, will have a substantial drop in octane of 2 to 4 points. E.G. After water contamination, E10 gasoline purchased with 87 octane will drop to about 83 to 84.
Fuel-Testers, a division of MLR Solutions www.fueltestkit.com - www.fuel-testers.com (631) 532-9447
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Octane gas issues/problems, when fuel contains ethanol alcohol: