Quote Originally Posted by sebtoombs View Post
actually, thats not true. a fuel with a higher RON rating has a higher temp/pressure at which it will combust. This is due to the presence of branched chains etc within the molecule which limit the availability of oxygen to the carbon atoms. So a fuel with a higher octane rating will help to prevent pre-ignition (knocking) in a high compression engine (hence its use in turbo cars), or with far advanced timing. It also burns slower and in a more controlled fashion.
However if your car is tuned (standard or not) to run above 91 RON then you will certainly see a difference. I wouldn't use less than 95 personally, just how I roll and I 'save money' in more effective ways LOL

OP, just drive until your light comes on, then re-fill etc. My needle doesn't drop until I've done 130+ KMs. I usually get 450km before my light comes on.