Fuel
Popular Reply
Nov 16, 2024, 02:56 PM
Moderator
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From: DFW Area TX
Race Director
Joined: Mar 2007
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I use 93 Octane, TopTier when its available. "Licensed TOP TIER™ Gasoline Retailers must adhere to the rigorous fuel detergency performance requirements." It is not a fuel stabilizer. Per the manual the minimum octane for street use is 91. In the Track Events and Competitive Driving section of the manual, it recommends 93 Octane.
Racer
Joined: Apr 2006
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From: Houston Texas
Racer
Joined: Aug 2024
Posts: 398
Likes: 320
From: Naples FL
What gasoline is not "Top Tier"? I have never seen gas that did not in some way claim to be Top Tier. Even the no name stuff that people wait in line for to save a few bucks at Costco has Top Tier description.
I have read many internet forum posts about how all gasoline comes out of the same monster tanks with name brand fuel receiving additives to the tank truck that it is delivered in. Would that not make all gasoline "Top Tier"?
I have read many internet forum posts about how all gasoline comes out of the same monster tanks with name brand fuel receiving additives to the tank truck that it is delivered in. Would that not make all gasoline "Top Tier"?
Moderator
Joined: Feb 2006
Posts: 39,188
Likes: 18,041
From: DFW Area TX
As for the Octane level, it depends on what year you have. For the 2020 (which I own), the Owner's Manual states:
Requirements have changed over the model years. OP, check the Owner"s Manual for whatever year you own. The recommendation to use Top Tier apples to all C8 years.
Fuel
Unleaded gasoline, rated at
93 octane or higher, is required.
Use premium unleaded gasoline
meeting ASTM specification D4814
with a posted octane rating of 93 —
(R+M)/2. If unavailable, unleaded
gasoline with a posted octane rating
of 91 may be used, but with reduced
performance and fuel economy.
If the octane is less than 91, the
engine could be damaged and the
repairs would not be covered by the
vehicle warranty. If heavy knocking
is heard when using gasoline rated
at 93 octane, the engine needs
service.
Do not use any fuel labeled E85 or
FlexFuel. Do not use gasoline with
ethanol levels greater than 15% by
volume.
Unleaded gasoline, rated at
93 octane or higher, is required.
Use premium unleaded gasoline
meeting ASTM specification D4814
with a posted octane rating of 93 —
(R+M)/2. If unavailable, unleaded
gasoline with a posted octane rating
of 91 may be used, but with reduced
performance and fuel economy.
If the octane is less than 91, the
engine could be damaged and the
repairs would not be covered by the
vehicle warranty. If heavy knocking
is heard when using gasoline rated
at 93 octane, the engine needs
service.
Do not use any fuel labeled E85 or
FlexFuel. Do not use gasoline with
ethanol levels greater than 15% by
volume.
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Moderator
Joined: Feb 2006
Posts: 39,188
Likes: 18,041
From: DFW Area TX
What gasoline is not "Top Tier"? I have never seen gas that did not in some way claim to be Top Tier. Even the no name stuff that people wait in line for to save a few bucks at Costco has Top Tier description.
I have read many internet forum posts about how all gasoline comes out of the same monster tanks with name brand fuel receiving additives to the tank truck that it is delivered in. Would that not make all gasoline "Top Tier"?
I have read many internet forum posts about how all gasoline comes out of the same monster tanks with name brand fuel receiving additives to the tank truck that it is delivered in. Would that not make all gasoline "Top Tier"?
Racetrack is an example of fuel that is not Top Tier. While Costco is Top Tier, neither Sam's nor Murphy (Walmart) is Top Tier.
The number of Top Tier brands has increased over time, but there are definitely non-Top Tier brands.
CF Community Team
Joined: Nov 2005
Posts: 5,270
Likes: 2,907
From: Charlotte N.C.
Intermediate
Joined: Oct 2024
Posts: 37
Likes: 24
From: Austin. TX
What gasoline is not "Top Tier"? I have never seen gas that did not in some way claim to be Top Tier. Even the no name stuff that people wait in line for to save a few bucks at Costco has Top Tier description.
I have read many internet forum posts about how all gasoline comes out of the same monster tanks with name brand fuel receiving additives to the tank truck that it is delivered in. Would that not make all gasoline "Top Tier"?
I have read many internet forum posts about how all gasoline comes out of the same monster tanks with name brand fuel receiving additives to the tank truck that it is delivered in. Would that not make all gasoline "Top Tier"?
Race Director
Joined: Mar 2007
Posts: 11,462
Likes: 8,633
The wording of the requirement changed, but 91 has always been the minimum octane requirement. In the earlier manuals it recommended 93 octane, but then goes on to say If unavailable, unleaded gasoline with a posted octane rating of 91 may be used, but with reduced performance and fuel economy. If the octane is less than 91, the engine could be damaged and the repairs would not be covered by the vehicle warranty.
In later years the manual says 91 is required, but then it also required 93 in the Track Events and Competitive Driving section.
I use 93. Also, if you can't find Top Tier, the manual says "ACDelco Fuel System Treatment Plus−Gasoline to the vehicle’s gasoline fuel tank at every oil change or 15 000 km (9,000 mi), whichever occurs first. TOP TIER Detergent Gasoline and ACDelco Fuel System Treatment Plus−Gasoline will help keep your vehicle’s engine fuel deposit free and performing optimally."
In later years the manual says 91 is required, but then it also required 93 in the Track Events and Competitive Driving section.
I use 93. Also, if you can't find Top Tier, the manual says "ACDelco Fuel System Treatment Plus−Gasoline to the vehicle’s gasoline fuel tank at every oil change or 15 000 km (9,000 mi), whichever occurs first. TOP TIER Detergent Gasoline and ACDelco Fuel System Treatment Plus−Gasoline will help keep your vehicle’s engine fuel deposit free and performing optimally."
CF Community Team
Joined: Apr 2016
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From: Pittsburgh
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If 93 octane is available in your area, I would use it
Le Mans Master
Joined: Feb 2008
Posts: 5,644
Likes: 1,220
From: Lake Worth Beach, Florida
Le Mans Master
Joined: Feb 2008
Posts: 5,644
Likes: 1,220
From: Lake Worth Beach, Florida
The wording of the requirement changed, but 91 has always been the minimum octane requirement. In the earlier manuals it recommended 93 octane, but then goes on to say If unavailable, unleaded gasoline with a posted octane rating of 91 may be used, but with reduced performance and fuel economy. If the octane is less than 91, the engine could be damaged and the repairs would not be covered by the vehicle warranty.
In later years the manual says 91 is required, but then it also required 93 in the Track Events and Competitive Driving section.
I use 93. Also, if you can't find Top Tier, the manual says "ACDelco Fuel System Treatment Plus−Gasoline to the vehicle’s gasoline fuel tank at every oil change or 15 000 km (9,000 mi), whichever occurs first. TOP TIER Detergent Gasoline and ACDelco Fuel System Treatment Plus−Gasoline will help keep your vehicle’s engine fuel deposit free and performing optimally."
In later years the manual says 91 is required, but then it also required 93 in the Track Events and Competitive Driving section.
I use 93. Also, if you can't find Top Tier, the manual says "ACDelco Fuel System Treatment Plus−Gasoline to the vehicle’s gasoline fuel tank at every oil change or 15 000 km (9,000 mi), whichever occurs first. TOP TIER Detergent Gasoline and ACDelco Fuel System Treatment Plus−Gasoline will help keep your vehicle’s engine fuel deposit free and performing optimally."
On a road trip in 2014 I could only get 91 octane on the east side of the Rockies. Amazingly I was getting 40 + MPG at altitude at 80 MPH in my C6 M6.
Possibly one of you guys who live at altitude can explain.
CF Community Team
Joined: Nov 2005
Posts: 5,270
Likes: 2,907
From: Charlotte N.C.
I do less than a tank a month, usually 1/4 to 1/2 tank. We do the Harris Teeter $1 off and fill my wife’s car and my van and get two 5 gallon cans for $1.89 a gallon. High test is about $4. You do the math. I don’t do it every month, just now and then. It doesn’t bother me.
Also top off my motorcycles with the 5 gallon cans… Or use them later in the van.
Also top off my motorcycles with the 5 gallon cans… Or use them later in the van.
Moderator
Joined: Feb 2006
Posts: 39,188
Likes: 18,041
From: DFW Area TX
The wording of the requirement changed, but 91 has always been the minimum octane requirement. In the earlier manuals it recommended 93 octane, but then goes on to say If unavailable, unleaded gasoline with a posted octane rating of 91 may be used, but with reduced performance and fuel economy. If the octane is less than 91, the engine could be damaged and the repairs would not be covered by the vehicle warranty.
In later years the manual says 91 is required, but then it also required 93 in the Track Events and Competitive Driving section.
I use 93. Also, if you can't find Top Tier, the manual says "ACDelco Fuel System Treatment Plus−Gasoline to the vehicle’s gasoline fuel tank at every oil change or 15 000 km (9,000 mi), whichever occurs first. TOP TIER Detergent Gasoline and ACDelco Fuel System Treatment Plus−Gasoline will help keep your vehicle’s engine fuel deposit free and performing optimally."
In later years the manual says 91 is required, but then it also required 93 in the Track Events and Competitive Driving section.
I use 93. Also, if you can't find Top Tier, the manual says "ACDelco Fuel System Treatment Plus−Gasoline to the vehicle’s gasoline fuel tank at every oil change or 15 000 km (9,000 mi), whichever occurs first. TOP TIER Detergent Gasoline and ACDelco Fuel System Treatment Plus−Gasoline will help keep your vehicle’s engine fuel deposit free and performing optimally."
