Howdy, folks! It's good to be here. I picked up my 2008 Coupe G37S a few days ago. I live in the UAE (United Arab Emirates). The fuel types we have here are: "E-plus" at 91 octane, "Special" at 95 octane and "Super" at 98 octane. The previous owner ran 98 octane fuel on it. He said it was the best fuel type for the car. It didn't make much sense to me because although it says in the service manual that "INFINITI recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research octane number 96)," the most premium pump fuel type in the USA is 95 octane. So the question is,, is using 98 octane overkill? Wouldn't it be better if I dialed it back to 95?? What do you good people think??

 

98 in UAE is equivalent to 93 here in the states. 95 is equivalent to 91.

The US using RON + MON/2. A lot of other places only use RON.

 

Just curious about what fuel costs are in in UAE? Can anybody provide some contrast with what USA costs are?

 

If 98 is indeed the 93 oct equivalent then yes it will be the best octane for the car. Period.
Lower octanes will result in lower performance.

 

Unless his car is tuned for the higher octane rating, paying more for fuel that's above operating specs is just a silly waste of money.

 

Well, based off Uprev I can see more knock count running on 91 VS 93.
Granted I'm not tuned on either fuels but I'm sure OP will notice a difference.
OEM ECM will retard the necessary timing to stop the knock so technically on an OEM ECM he'll be fine with anything 90+ octane.