E10 Gas has a maximum shelf life of only 3 months.
Gas Expiration - Ethanol Blend Fuels Have a Short Shelf Life
When exposed to water, E10 gas will contaminate and should be discarded.
Phase separation occurs in E10 gas, when only 0.5% water or 3.8 teaspoons water per gallon of fuel is absorbed!
Ethanol gasoline is hygroscopic (will absorb water) and can absorb 50 times more water than conventional non-alcohol gasoline.
Only about 1 tablespoon of water/per gallon will cause fuel to contaminate/separate.
At 70 degrees Fahrenheit, conventional (non-alcohol) gasoline can dissolve up to 150 ppm (parts per million) water.
The situation is different for gasoline oxygenated with 10% volume ethanol -
The ethanol blend can dissolve much more water, up to 6000-7000 ppm.
When this blend is cooled, both the water and some of the ethanol become insoluble.
Replace gas in your fuel tank every 2-3 weeks to avoid water related engine problems.
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Several factors affect the shelf life of ethanol blend gasolines...
Gasoline blends without ethanol, have a shelf life of many years. The shelf life of E10 is lower due to ethanol's affinity to attract and absorb water.
The public has not been properly educated in the changes in fuel system management since the switchover to alcohol blends of fuel.
Even many gas stations owners, do not realize that E10 is expired (bad fuel) only after about 90 days from the date ethanol was added to the gasoline.
Often when tanks are not properly serviced before switching to ethanol blends of fuel, the water present at the bottom of tank will immediately contaminate the new E10 gas added.
All gas supplied to the public contains preservatives - But this perservatives and stabilizers do almost nothing to prevent water contamination.
Foolishly, many consumers are adding extra "additives" to their gas tanks that sometimes deceptively claim they will prevent ethanol water absorption - No product/additive with this capability exists.
Oil based stabilizers and fuel conditioners may help tom protect other undesireable side effects of ethanol, such as drying and solvent effects that wear down parts. View other negative engine effects from ethanol.
No product exists that will prevent water absorption by alcohol.
Some additives delay phase seperation, but fuel will still contain excess water.
All alcohols have a natural affinity for water. By nature, they attract and absorb moisture.
Whether or not the alcohol is in a medical, cleanser, beverage or fuel - All alcohols attract water.
It's the "water absorbing" properties that makes ethanol gas most problematic and difficult to manage.
- Petroleum does not blend with water.
Therefore, when excess water enters fuel supply, gasoline will phase separate.
- Phase-separated gas is contaminated and should never be used in engines.
Not only does separated fuel create obvious problems, (E.G. poor performance and release of water into engine causing rusting of parts), phase seperation will also distort the hundreds of other ingredients that gasoline contains.
- Water-contaminated and phase-seperated fuel will experience a drop in octane.
Click here for information on OCTANE of ethanol fuel blends.
Outboard and marine companies recommend you use fuel within 2-4 weeks, store tanks empty for winter...
View Engine Manufacturer Fuel Recommendations and Warnings.
Marine Problems with Ethanol Fuels is primarily due to rapid water contamination of gasoline...
More Information:
Phase Separation
With the process of phase separation, two layers of liquid are visible.
An upper ethanol-deficient gasoline layer and a lower ethanol-rich (usually contains up to 75% ethanol) water layer.
It occurs because ethanol is completely soluble in water but only marginally soluble in hydrocarbons...
After phase separation, the gasoline layer will have a lower octane number. The fuel also is less volatile.
Precautions
When using fuels that contain alcohol/ethanol, simple precautions are necessary to prevent contamination by water.
The amount of ethanol blended in at the pumps, is not closely monitored.
The ethanol is not added at the major refineries - Usually it is the delivery truck driver or local fuel distributor who adds the ethanol to fuel supply.
Checking that gasoline meets safe and legal alcohol guidelines (10% or lower) and has not absorbed water is recommended, until more stringent and protective E10 consumer laws are passed.
Refilling often, with high quality, fresh gasoline, is the best measure you can take to manage the shorter shelf life and higher risk of water contamination that occurs when using E10 and other alcohol fuel blends.
Check your STATE ETHANOL LABELING LAWS
032009 0130
E10 Gas has a maximum shelf life of only about 3 months.
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Everything you need to know to safely manage ethanol & E10 gasoline...
