The owners manual says:
INFINITI recommends the use of unleaded premium gasoline with an octaine rating of at least 91 AKI (Anti-Knock Index) number (Research octaine number 96).

So now I am wondering:
Which rating is actually shown on the pump, the AKI number or the Research octaine number?

For those of you asking about fuels containing alcohol, the owners manual goes on to state:
Some fuel suppliers sell gasoline containing oxygenates such as ethanol, MTBE, and methanol...INFINITI does not recommend the use of fuels of which the oxygenate content and the fuel compatability for your INFINITI cannot be redily determined...If you use oxygenate-blend gasoline please take the following precautions as the usage of such fuels may cause vehicle perfomance problems and/or fuel system damage.

(I'll summarize the precautions)
Oxygenated fuel should be unleaded and have an octaine rating no lower than mentioned above.
Ethanol blends should not contain more than 10% ethanol
Methanol blends should not contain more than 5% methanol
MTBE (whatever that is) should not exceed 15%

 

i used 93 BP/amaco octane gas octane and mobile one syntech in my 02 sentra specv for over 4 years of serious/spirited driving before i busted it apart for a headgasket failure(thanks to running out of gas during its maiden boosted trip to do some racing-ran through half tank-5.5gal- in 20 minutes of fun).....

Valve/Head/Pistons/Cylinder walls were spotless and looked like they were fresh out of the machine shop. i am a strong believer in using synthetic oils and premium gas. Your motor will last longer and your gas mileage should be better.

 

In CA, what you see is (MON + RON ) /2

RON is the research octane number (also the only figure a lot of countries go by, including japan)

 

the most we can get here in CO is 91, or E85 at some pumps. I used to use E85 in my boosted honda, loved that ****. I am all to fimilar with "knock", car I sold to get my G was a 578hp car. good to know about the 10% rule though.