Somewhat of a duplicate post, but:
I run 87, as 93 showed no noticeable improvement. I wonder (suspect) that the "91" in the service manual might be RON while we use AKI in the US.
91 RON ~ 87 AKI
Octane rating - Wikipedia, the free encyclopedia
~
In other news, I discovered what a low 12v battery is like in our cars. I posted over on InsightCentral about it, and their best guess was that one of the cells inverted, because I was unable to put more than about 8-9v in my battery even leaving it on charge overnight. Symptoms of a 12v battery:
Turn key, and the display comes on, but with no backlight. Car starts using the backup starter (and amazingly, starts with only 8v). FCD button does not work. Odometer does not go up when driving. Tons of warning lights are on, including EPS, ABS, battery, parking brake and seatbelt. Odometer still shows RPM when driving, but I don't think the engine temperature gauge ever went up. Battery gauge reads empty. Power steering does not work. Car drives strange, pressing the pedal to the floor causes it to shudder and buck, need to feather the pedal to get up to speed. No electric assist or regenerative braking. I have a suspicion that the DC-DC converter also was not coming on.
Despite all this, I was able to drive to classes and later take it to Honda for a new battery. I wonder if using my maintainer ever night killed my 12v? It was about 5 years old, but its death was very sudden. For now, I'm leaving the charger in place but will not be using it nightly.