[Jeroen]

I am a little confused here on some of the points raised

An engine has a certain, in essence fixed, compression, which means that it is designed for a certain octane number, e.g. 93. Putting a higher octane number fuel in that engine won't do a thing.

The octane numer is a measure to avoid knock effects. The other way around it would definitely affect engine performance in a negative way.
So if an engine is designed for say an octane number of 98 and you put it a fuel with an octane number of say 93, you could well induce engine knock.

Unless it's different in India, the octane number doesn't say anything about the iso -octane, or any property of the actual fuel in your tank. It's a comparitive test that determines the octane number. The USA measures it differently from Europe, so India might be different again, but the basic principle remains the same

So the increase in the octane number has no bearing on engine performance. The toluene will, at least in theory, increase the energy per unit, that you can extract from the fuel. I'm not sure on the real world affect, but if they are considerable I would be concerned on engine wear, mid to long term.

Jeroen

[alpha1]

Originally Posted by coolbareilly

Sorry for bumping into old thread, but was curious to ask experts on 93 Octane Fuel:

Quite late I have seen most of the IOC pumps have started selling 93 Octane petrol in Delhi. Can you please let me know, if I can use the same for my 2010 City A/T? If yes, what will be the advantages over non-branded fuel? If No, then whats the reason behind it? Does Engine doesnt supports it or Honda doesnt recommends, which may void the extended warranty ?

No advantage.

As Jeroen has already noted, an engine is designed for a certain Octane number. Higher than that will not harm the engine, neither will give you any benefit. Lower than that will definitely harm your engine.

If any company like IOC shows benefit like higher mileage, lower fuel consumption - then it is complete loads of marketing baloney for suckers (= consumers in modern world).