# 93 Octane w/ethanol or 87 ethanol free with Boost?



## Wilma (May 3, 2015)

My 1968 400 GTO ran great on 91 octane ethanol-free gas, which I can no longer get. All of the ethanol-free fuel sold near me is 87 octane. So, is it better to use an 87 octane blend with NO ethanol and add an octane booster, or should I use the 93 octane gas WITH ethanol and add a treatment (like StarBright) to deal with the bad stuff that can be caused by the ethanol? The car has the original mechanical fuel pump and Rochester Quadrajet.

Thanks in advance for your advice.


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## geeteeohguy (Feb 2, 2008)

If it's only 10% ethanol, you'll be ok. If you run the non-ethanol 87 octane fuel, you will need a real octane booster that actually works like Octane Supreme 130 or you will have to add a little race gas. The 104+ and 108+ octane boosters and all the others sold at the parts stores are an absolute waste of time and money. They do not work in the slightest. Been running both of mine on 91 octane with 10% ethanol for years with no problems, but have to add race gas or Octane Supreme to the '65, which still has high compression. Good luck.


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## GTO JUDGE (May 14, 2005)

Wilma said:


> My 1968 400 GTO ran great on 91 octane ethanol-free gas, which I can no longer get. All of the ethanol-free fuel sold near me is 87 octane. So, is it better to use an 87 octane blend with NO ethanol and add an octane booster, or should I use the 93 octane gas WITH ethanol and add a treatment (like StarBright) to deal with the bad stuff that can be caused by the ethanol? The car has the original mechanical fuel pump and Rochester Quadrajet.
> 
> Thanks in advance for your advice.


I run Sunoco 93 Oct in my 400 and I put a lot of miles on the car during the season. Been using Lucas Ethanol Treatment the past 4 years. Last year I used Octane Supreme with Lead to raise the Oct. to 98. I didn't notice any difference other than the expense. I returned to adding the Ethanol treatment. 1oz per 5 gallons. Car runs great. I keep a bottle and funnel in my trunk. 
Ethanol Free 100 oct here is 9.00 a gallon. I drive the car too much to be using it. Some who barely put miles on their car go to a local airport and get aviation fuel which is $$$.


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## geeteeohguy (Feb 2, 2008)

If your car doesn't ping on 93 octane, adding Octane Supreme will do you no good. It raises octane.....and you should always run the lowest octane you can without the engine pinging. Lower octane fuel has more energy because it burns faster. The higher the octane, the slower the burn and the lower the energy. Hi octane ratings are needed in engines with very high compression in order not to pre-ignite. My 11:1 389 pings on 91 octane, and doesn't ping when I boost the fuel to 98-100 octane. Works for me.


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## advchaser (Jan 9, 2017)

Did you make any additional modifications to your car to protect it against the ravages of ethanol fuel? 
Thanks!


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## silver64vert (Jan 22, 2017)

When I first got my car it seemed like it didn't have alot of power so I advanced the timing alittle @ a time till it started pinging & backed it off.I'm using Shell 93 oct it made a big difference in power.I think it was backed off to run 87 oct.


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## 1968gto421 (Mar 28, 2014)

I found a station up on State Park Rd and Altamont that still has the 93 octane ethanol free gas. Also Willis up in TR has it, too. They're in the fork of the streets just down from the TR Library. Hope this helps.

Also here is a link that may help---- Ethanol-free gas stations in the U.S. and Canada

FYI--- I bought 110 octane race gas at Greer Dragway in my 5 gallon can for a pinging problem Im working on with my '68.


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