Phase Separation in
Ethanol Blended Gasoline’s
Phase Separation in Gasoline’s containing Ethanol is now a
major problem for all users of gasoline.
Whether you use gasoline as a fleet operator or for your family car, classic
car, boat, personal water-craft, motorcycle, snowmobile, ATV, RV, lawnmower,
weed-whacker, generator, or any of the thousands of other types of equipment
that use gasoline engines; you are being affected by Ethanol in your fuel.
Phase Separation describes what happens to gasoline containing Ethanol when
water is present. When gasoline containing even small amounts of Ethanol comes
in contact with water, either liquid or in the form of humidity; the Ethanol
will pick-up and absorb some or all of that water. When it reaches a saturation
point the Ethanol and water will Phase Separate, actually coming out of solution
and forming two or three distinct layers in the tank.
Phase Separation is also temperature dependent. For example, E-10 can hold
approximately .05% water at 60°F. To better understand the amount of water that
we are talking about, picture 1 gallon of E-10 at 60°F. This gallon will hold
approximately 3.8 teaspoons of water. However if the temperature drops to 20°F
it can only hold about 2.8 teaspoons of water.
We recently were called to consult for a fleet where a fairly large number of
vehicles were being regularly fueled from a single tank and about one-half the
vehicles were stored inside and the other half were stored outside. After a
night with a 30°F+ temperature drop, several of the vehicles stored outside
developed problems with significant amounts of water found in the vehicle tanks.
After checking the storage tank and finding no measurable water, they looked for
other possible causes including sabotage. After looking at many possible causes
this customer consulted with us and we were able to describe the Phase
Separation through temperature change scenario and determine that this was the
most likely cause of the problems.
Phase Separation can happen in an underground or an
storage tank, a vehicle tank, a boat tank, in any type of equipment tank, and
even in the gas can in your garage.
When this happens, you can have serious and even catastrophic engine problems,
When this Phase Separation occurs you will have an upper layer of gasoline with
a milky layer of Ethanol and Water below it, and then in many cases a third
layer of just water at the bottom.
If this happens and you try to start the engine you can have one or more of the
following problems. If your fuel tank pick-up tube is in the water layer, most
likely the engine will fail to start. If the engine is running and suddenly
draws water you can have damage from thermal shock or hydro-lock. If the pick-up
tube draws the Ethanol-Water mixture or just Ethanol you can have problems where
the engine will operate in an extreme lean condition, which can cause
significant damage or even catastrophic failure. If the pick-up tube draws the
gasoline, it will operate very poorly due to lower octane that is the result of
no longer having the Ethanol in the fuel.
Gasoline containing Ethanol provides further challenges and dangers for marine
operators (Boaters) and other users of seasonal equipment such as motorcycles,
personal water-craft, snowmobiles, ATV’s, RV’s, yard maintenance, generators,
and other equipment.
Ethanol is a strong, aggressive solvent and will cause problems with rubber
hoses, o-rings, seals, and gaskets. These problems are worse during extended
storage when significant deterioration will take place. Hoses will
o-rings will soften and break down, and fuel system components made from certain
types of plastics will either soften or become hard and brittle, eventually
failing. Fuel system components made from brass, copper, and aluminum will
oxidize to the point of failure.
Operators of boats with fiberglass fuel tanks built before 1993 can have actual
structural failure as Ethanol will break down and pick-up some of the materials
the tanks are made from. This causes two separate but equally serious problems.
First the tanks can become so weakened that they can fail. In cases where the
tank is part of the boats structure we have seen tanks become so weak that it is
possible to collapse part of the deck just by walking on it. The second problem
is that this material when dissolved from the fiberglass tank is carried through
the fuel system and can cause damage to carburetors and fuel injectors and can
actually get into the combustion chambers causing damaging deposits on valves
and pistons. This material can be nearly impossible to remove without destroying
the affected parts.
Two-Cycle engines have a special problem with Ethanol blended fuels. Two-Cycle
engines function because the oil added to the fuel bonds to the engines metal
surfaces and provides barrier lubrication to all the parts requiring
lubrication. When Ethanol is added to the gasoline, it displaces the oil and
forms a primary bond with the metal surfaces. This bond provides virtually no
lubrication and can result in significantly increased wear and even catastrophic
failure in a very short amount of time.
Until now the only preventative measures available to tank operators and end
users was to try and make sure there was no water in the tank and that vents
allowed a minimum amount of airborne water (humidity) into the tank.
Gasohol, E-10, E-20, and E-85 are the terms that refer to gasoline containing
Ethanol. For example the most common fuel available today is E10. E-10 is 10%
Ethanol and 90% gasoline, while E-85 is 85% Ethanol and 15% gasoline (Note: E-85
is actually E-70 in the winter in cold weather (Northern Tier) states.
Ethanol has less energy (as measure in Btu’s – British Thermal Units) per gallon
than does regular unleaded gasoline. This means that the more Ethanol found in
fuel the worse your fuel economy will be. You use more gallons of fuel
containing Ethanol to go fewer miles.
This poor fuel economy is made worse by other EPA and State requirements for
fuels to change seasonally. Until very recently we have used what is known as
“Conventional” gasoline (CVG)
in the winter and “Reformulated gasoline (RFG)
in the summer. The theory is that the lower volatility of
RFG will reduce
the formation of green house gases. However
RFG has lower
Btu’s per gallon. RFG
together with Ethanol results in a significant mileage penalty. My own vehicle
drops about 2 miles per gallon or about 9% when using
RFG with Ethanol.
For many years the refining industry used a chemical called
MTBE to meet the
oxygenate requirements set forth by the EPA. Generally refiners used 15%
MTBE and 85%
gasoline. However MTBE
has now been virtually eliminated in the US due to its carcinogenic compounds
and the huge potential problems caused by its pollution of as much as 75% of the
ground water in the US and Canada.
This has left Ethanol as the primary additive to meet Federal and State
Further the federal government currently subsidizes Ethanol with a $.51 per
gallon tax credit that goes to the refiners or blenders. With E-10 this provides
those refiners and or blenders with a $.051 per gallon subsidy on every gallon
of gasoline that they sell.
In many cases we have seen gasoline containing more than 10% Ethanol. We test
regularly and have seen fuel containing 12%, 13%, and even 14% Ethanol while the
pump shows only 10%. Increasing the amount of Ethanol increases the
refiner/blenders subsidy and profit while further lowering your fuel economy.
One more concern with Ethanol and
RFG or Ethanol
and CVG is that
Ethanol when mixed with water; they readily form Gums in the fuel system much
quicker than gasoline without Ethanol. These Gums coat fuel system components
including filters, carburetors, injectors, throttle plates; and will then form
varnish and carbon deposits in the intake, on valves, and in the combustion
chamber. These deposits can coat sensors and plug catalytic converters.
The good news is that we now have products available to prevent and control
Phase Separation and that we can dramatically reduce or eliminate most of the
problems caused by Ethanol in Gasoline.
Because of all the problems with Ethanol Blended gasoline’s we will list some
specific suggestions and recommendations on how to deal with and resolve many of
When Phase Separation occurs in fuel tank on a vehicle, boat or other piece of
equipment, the tank should be completely drained. The tank should be refilled
with good fuel and the fuel line purged prior to restarting the engine.
For Seasonal vehicles and equipment, e.g. boats, personal water-craft,
motorcycles, classic cars, ATV’s, RV’s, lawn and garden equipment, gasoline
powered generators, and so on, we recommend that you try to use conventional
gasoline without Ethanol whenever possible and particularly prior to storage.
In ALL Two-Cycle gasoline engines where there is any possibility that you are
using gasoline containing Ethanol we strongly suggest using a full synthetic
two-cycle oil in the gas.
In bulk storage tanks where you believe phase separation may have occurred or
where you are concerned it may happen. We suggest the use of a modified water
finding paste such is made by the
This paste starts out brown, if you dip the tank with a measuring stick with the
paste and it turns yellow (even light or spotty yellow), you have significant
water dissolved in the fuel, if the paste turns red you have free water.
If you have fuel that has Phase Separated and you have either two or three
layers you should arrange to have the tank pumped from the bottom to remove the
one or two bottom layers containing the water and or the Ethanol/Water mix.
(Note: you should check again with the paste before the technician leaves to be
certain that all the Water and Water/Ethanol has been completely removed). You
do not need to remove the gasoline. Check with water finding paste after 24
hours. If no red or yellow present then add clean fuel to the tank to working