: Question on switching from Premium to Ethanol Blended gas



2000STSOwner
05-07-04, 04:30 AM
I have a 1996 Olds Aurora that requires premium (according to the owners manual). When I got the car back in 1998 the dealer told me he spoke to some engineers from GM and they said to only use premium, no ethanol. "It wasn't designed to burn corn..."

With premium now at $1.99 I'm planning to switch to ethanol blended gas. The premium around here is 91 octane and the ethanol stuff is 89-90 octane.

What kind of long term problems could I be opening myself up for? I don't drive this car everyday, but that may change soon.

Any suggestions would be appreciated.

STS
05-07-04, 10:41 AM
i put 93 in my STS (premium is 93 here in FL, where do you live that you're getting ripped off at 91?)

every other 2 fill ups i'll put 89 in it, no probs yet at 230k

2000STSOwner
05-07-04, 01:11 PM
I live in Iowa. 93 is available at the BP stations, but it's even more that the 91 premium.

BeelzeBob
05-07-04, 02:47 PM
I have a 1996 Olds Aurora that requires premium (according to the owners manual). When I got the car back in 1998 the dealer told me he spoke to some engineers from GM and they said to only use premium, no ethanol. "It wasn't designed to burn corn..."

With premium now at $1.99 I'm planning to switch to ethanol blended gas. The premium around here is 91 octane and the ethanol stuff is 89-90 octane.

What kind of long term problems could I be opening myself up for? I don't drive this car everyday, but that may change soon.

Any suggestions would be appreciated.


It will be fine. The engine will run on properly blended ethanol fuel fine....


Just realize that it may be a false economy, though. Basically, it takes twice as much alcohol (methanol or ethanol) as gasoline to run the engine. This is just basic chemistry.... For each gallon of gasoline it takes two gallons of alcohol to achive the SAME ,chemically correct, A/F ratio for the engine. So....if you put in ethanol fuel that is 10 percent ethanol the engine is going to be instantly 5 % lean...and the onboard controls will richen the system up to compensate. The engine is still "seeing" the same amount of HC fuel coming in...it just takes twice as much alcohol (by volume) to achieve that chemically correct range. So...fuel economy will instantly decrease by about 5% using fuel that is 10% ethanol. So, expect worse fuel economy. This is just chemistry, as I said. It happens with every engine in every car that runs on alcohol fuels. Worst case is pure alcohol. If you were to run pure alcohol the mileage would instantly go to 1/2 of what it was..... so if you were getting 20 MPG on gasoline you would get 10 MPG on pure ethanol.... Something the "alcohol advocates" always forget to tell you....

Considering the cost difference and the poorer fuel economy with the alcohol fuels it may cost more to drive the car on the alcohol fuel.

What percentage of alcohol is in the fuel?? GM recommends a maximum of 10 percent for that car and fuel system I believe. The computer cannot correct for greater percentages as well and driveablility may sufffer.

I would try running just plain regular fuel if cost is an issue. The knock sensor will protect the engine adequately and you will probably not even notice a difference in driveability and fuel economy.


Typically gasolines in the mid west towards Iowa start to have lower octane fuels as premium as the altitude is greater than Florida...so the air pressure is slightly lower and the maximium charge density in the engine is slightly less...requiring less octane rating in the fuel. What is the altitude where you are at.??

Ralph
05-08-04, 12:41 AM
What percentage of alcohol is in the fuel?? GM recommends a maximum of 10 percent for that car and fuel system I believe. The computer cannot correct for greater percentages as well and driveablility may sufffer.



Yup, my owners manual says Ethanol or grain alcohol, properly blended and no more than 10% is fine. We have a couple of different gas stations that mix it up to 5 or 6 percent, I believe. They also say that is burns cleaner for the environment.