Fuel additive
Race Director
Joined: Jan 2014
Posts: 10,709
Likes: 7,102
From: Fulshear, TX
Octane booster is fine, otherwise you could get real fancy and splash blend your own 93 by adding 2 gallons of E85 per tank since I assume what you do have available is 91 E0. Splash blending in 2 gallons of E85 will get you roughly the same product (octane and ethanol content) as a typical 93-octane pump fuel. That's what I've done when in certain areas without access to 93 
Melting Slicks
Joined: Aug 2000
Posts: 2,428
Likes: 1,199
From: Early 2020 Z51 Coupe, Original Owner, Ahwatukee Foothills, AZ
Or if you have 100 octane unleaded race fuel available splash blend in 2-3 gallons to the 91 octane. Don't use the 110 octane, it's leaded // cat killer.
This is what I do in AZ with only 91 being the highest available.
This is what I do in AZ with only 91 being the highest available.
Race Director
Joined: Aug 2016
Posts: 12,805
Likes: 10,224
From: Garden Valley CA
Most octane boosters have MMT. The owner's manual specifically warns not to use fuels with MMT:
"Fuel containing metals such as methylcyclopentadienyl manganese tricarbonyl (MMT), which can damage the emissions control system and spark plugs."
If your concern is damaging the engine by running a lower octane, as long as you're using 91 or above you'll be OK:
"If unavailable, unleaded gasoline with a posted octane rating of 91 may be used, but with reduced performance and fuel economy."
You're safer using 91 octane than an octane booster and you won't notice the performance difference (if any) by the seat of your pants.
If your doing timed events then try mixing your own 93 octane as recommended above.
"Fuel containing metals such as methylcyclopentadienyl manganese tricarbonyl (MMT), which can damage the emissions control system and spark plugs."
If your concern is damaging the engine by running a lower octane, as long as you're using 91 or above you'll be OK:
"If unavailable, unleaded gasoline with a posted octane rating of 91 may be used, but with reduced performance and fuel economy."
You're safer using 91 octane than an octane booster and you won't notice the performance difference (if any) by the seat of your pants.
If your doing timed events then try mixing your own 93 octane as recommended above.
Burning Brakes
Joined: Sep 2019
Posts: 1,089
Likes: 668
From: Orange County, CA
You dont need an additive. The engine computer will compensate for the fuel. 93 is recommended for peak performance.
95% of people dont use peak performance. Unless you are racing competitively I wouldn't worry about it.
All owners in CA have is 91 swill. Ive been on it for a year and so have thousands of other C8 owners in CA.
Dont over think it.
95% of people dont use peak performance. Unless you are racing competitively I wouldn't worry about it.
All owners in CA have is 91 swill. Ive been on it for a year and so have thousands of other C8 owners in CA.
Dont over think it.
Last edited by GTUnit; Sep 11, 2021 at 07:19 PM.
