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100+ octane for my C4?

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The car runs fine on 91 octane. Going to 100 would not gain you anything but less money in your wallet, unless you have modified the engine. Raising the octane to 93 using a blend of 100 octane and 91 octane may provide you slightly better performance, but I am not sure if you would really notice.

If you're curious, it won't do any harm to try, but for a NA engine, I am sure you will see that it is a waste of money.

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A local gas station in my area offers 100+ octane racing gas (its a Union 76 station).  I was wondering what issue if any i would run into? I cant buy any better then 91, so i was wondering if i mixed it with 91 like 1/2 and 1/2 or should i just avoid it.


I have been mixing 1:4 of 100 octane for my car since it was new. It does run smoother, gets better gas milage, and the engine is quieter then when I take a straight tank of 91. I recommend the blend, but not a straight tankful.

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The only real way to see if a higher octane will increase performance is to look at what the computer is doing to the timing at WOT. Take a reading of the timing on regular fuel and then with the 100 octane. If for some reason the computer is retarding the timing with the regular fuel because it is too low an octane, you will see and higher timing with the 100 octane. If you don't, you most likely will not benefit in performance with the more expensive gas.

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