Author Topic: Ethanol in the tank  (Read 3968 times)


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Ethanol in the tank
« on: May 22, 2006, 08:18:17 PM »
As most people know by now, most gas being sold this summer is a 10% Ethanol blend. There are several known issues with Ethanol that concern me with regards to a older car. First, Ethanol acts like a detergent. Second, Ethanol asorbs water.

I don't know what the inside of my gas tank looks like, but after 38 years of service there has to be some kind of junk in it. Also, I don't get the Camaro but about once a month, so I'm also concerned about the gas asorbing water from the air as it sits.

I haven't seen any advice or recommendations on this subject, so I'm tossing it out here for discussion.

Should I be concerned? Should I fill the tank all the way up, knowing that it will be several months before I will have to do it again? Maybe I'm over-reacting, but I don't want to do anything that could cause damage to the car.

CRM - '68 RS/SS 396 L78


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Re: Ethanol in the tank
« Reply #1 on: May 22, 2006, 09:02:09 PM »
The following italics is from an Edelbrock document.  10% ethanoll blended gasoline will tend to clean the fuel system, so if it dirty, at the very least, you might need to change your fuel filter more frequently.  Keeping the gas tank full won't hurt, but since the system is vented, not sure how much good it will do.

Typically, two types of blended fuels are available: Gasohol and gasahol. Gasohol is a blend of not more than 10% ethanol and gasoline. As long as there is no more than 10% ethanol mixed with the gasoline you carburetor will function properly. As the percentage of ethanol climbs above10%, a richer A/F ratio will be required. Also, because gasohol is more volatile than gasoline, hard hot starting and poor hot weather driveability may result.

Gasahol can be a blend of either ethanol, methanol or other alcohol with gasoline. Methanol blended fuel should not be used as it will cause corrosion of the fuel system components. It can also cause rapid failure of seals, gaskets, diaphragms and pump plungers.

Always check to see if you are using a blended fuel. Although the pump may not indicate the fuel is blended, it is always advisable to verify the type of fuel the station carries.

As a side note to the statement above about richer with more than a 10% blend of ethanol.  Typical air / fuel ratio for gasoline is 14 - 15:1, for pure ethanol it is more like 9:1.
« Last Edit: May 22, 2006, 09:11:11 PM by rich69rs »
Richard Thomas
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Re: Ethanol in the tank
« Reply #2 on: May 22, 2006, 09:34:08 PM »
Not sure about the ethanol, but I've always been told to keep the tank full to minimize water in the fuel.  Also, look for a gas additive called "Stabil".  Pour in a bottle once a year.  Keeps gas "fresh", which is a good thing if your Camaro sits all winter long like mine.  A bottle of Dry Gas once in a while is good too.
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Re: Ethanol in the tank
« Reply #3 on: May 23, 2006, 02:40:40 AM »
Golden Eagle's "STA-BIL" is only one of several gas stabilizers you can and should use --if any gasoline powered motor is going to sit for a long period of time.  Ethanol or not, gasoline can eventually "break down".  If you do drive it once a month for several gallons, you are probably OK. 
If you are that concerned about your tank (I have seen tanks that sat for a long period of time that looked great on the outside but were all rust and sludge on the inside.) consider cleaning it or having it cleaned professionally.  Look at this from Chevy Trucks:
If your car sits a lot and/or you do not drive it many miles a year, you should also be changing your oil by the calendar, not just by miles.
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