Gas octane question
Thread Starter
Drifting
Joined: Sep 2010
Posts: 1,366
Likes: 105
From: Needham MA
Gas octane question
Now Z06 owner, so please forgive the basic question. In the C6's I always used Shell 93 octane, but in the Z06 manual I noticed it said to use the 91 octane. Just curious as to what octane gas most folks are using. Thanks.
Burning Brakes
Joined: Dec 2008
Posts: 767
Likes: 7
From: New Orleans Louisiana
NCM Sinkhole Donor
Melting Slicks
Joined: Oct 2007
Posts: 2,398
Likes: 858
There is a huge discussion to be had as to whether anything greater than 93ish will help without a tune.
Anything less than 91 will cause the car to revert "down to" one of the less agressive lower octane ingnition timing tables. This could reduce hp and mileage.
So keep running your 93 unless you cant get it.
Melting Slicks
Joined: Oct 2006
Posts: 2,976
Likes: 1,254
91 or more to a point is fine, the car is "tuned" fo the octane range , i.e. roughly 91-93, more is a waste of money. Best
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Michael S. Palmer
Instructor
Joined: Aug 2014
Posts: 140
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From: Westerville OH
Curious what your definition of a non top-tier supplier is. The fact is most stations are supplied by one of the "major" companies, although that is not to say all gasoline is created equal!
Melting Slicks
Joined: Aug 2000
Posts: 3,439
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From: Overland Park KS
I was told this by a gasoline delivery driver when he was filling up the tanks at one of our local fuel stations.
Bish
Le Mans Master
Joined: Sep 2009
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From: My interests are mobile
The top tier rated gasolines have more detergents to fight sulfur buildup and have been notorious for keeping the fuel level sending units in gas tanks operational...a problem for many gm vehicles. If you can use top tier it can only help, though I don't think a lesser fuel would hurt with occasional use.
Pro
Joined: Jul 2008
Posts: 611
Likes: 29
From: Old Saybrook, CT
I have a Gulf station that is close to my house, but Gulf isn't listed as a top-tier supplier.
Melting Slicks
Joined: Nov 2008
Posts: 2,186
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From: Virginia Beach VA
St. Jude Donor '10-'11-'12-'13-'14-'15-'16-'17,’18,’19
NCM Sinkhole Donor
TOP TIER Detergent Gasoline Retailers
Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline.
In addition, all gasoline outlets carrying the brand of the approved retailer must meet the TOP TIER standards.
Additional gasoline retailers are added to the TOP TIER list as they meet the standards. The retailers known to be on the TOP TIER list are shown below.
TOP TIER Gasoline Retailers:
USA
76 Stations
Aloha Petroleum
ARCO
Beacon
BP
Chevron
Conoco
Costco Wholesale
CountryMark
Diamond Shamrock
Entec Stations
Express Convenience Centers
Exxon
Hawaii Fueling Network (HFN)
Holiday Stationstores
Kwik Trip / Kwik Star
MFA Oil Co.
Mobil
Ohana Fuels
Phillips 66
QuikTrip
Road Ranger
Shamrock
Shell
Sinclair
Suncor Energy Inc
SuperAmerica
Texaco
Tri-Par Oil Co.
Valero
This comes from www.toptiergas.com.
Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline.
In addition, all gasoline outlets carrying the brand of the approved retailer must meet the TOP TIER standards.
Additional gasoline retailers are added to the TOP TIER list as they meet the standards. The retailers known to be on the TOP TIER list are shown below.
TOP TIER Gasoline Retailers:
USA
76 Stations
Aloha Petroleum
ARCO
Beacon
BP
Chevron
Conoco
Costco Wholesale
CountryMark
Diamond Shamrock
Entec Stations
Express Convenience Centers
Exxon
Hawaii Fueling Network (HFN)
Holiday Stationstores
Kwik Trip / Kwik Star
MFA Oil Co.
Mobil
Ohana Fuels
Phillips 66
QuikTrip
Road Ranger
Shamrock
Shell
Sinclair
Suncor Energy Inc
SuperAmerica
Texaco
Tri-Par Oil Co.
Valero
This comes from www.toptiergas.com.
Racer
Joined: Oct 2012
Posts: 349
Likes: 1
From: Orange County CA
I was thinking of using an octane booster on 91 this weekend at the track. I had read something by Tadge saying that will help the engine run cooler. He said using higher octane would, I'm wondering if this is a good way to try?
Melting Slicks
Joined: Aug 2000
Posts: 3,439
Likes: 977
From: Overland Park KS
As previously mentioned, adding a half tank of 100octane unleaded racing fuel to the 91 octane is excellent insurance against detonation.
Racer
Joined: Oct 2012
Posts: 349
Likes: 1
From: Orange County CA
Drifting
Joined: Jun 1999
Posts: 1,582
Likes: 2
From: Colorado Springs CO
The octane rating or addition of booster will make no difference to the engine operating temperature. Higher octane fuel is more resistant to pre-ignition (aka detonation) so it may help maintain more aggressive timing provided the ECU programming allows for such. If the ECU retards timing due to a combination of high ambient temperatures and how hard the car is tracked, octane booster can help. However, higher octane fuel is less combustible/explosive (primarily due to higher iso-octane/n-heptane ratios) so this can actually result in less power if the ECU programming is unable to take advantage through timing. The C7 Z06 is rated for 91 octane so for most track and driver situations, this would be the optimum fuel.