octane

[JIM NEWMAN]

Not sure this is the right place for this, but here it is - probably dumb question #342. Is it every inappropriate, cost notwithstanding, to use a higher octane fuel than your engine really requires? Can it possibly do any harm?
cheers
jim

 

[Steve_S]

From what I understand, running a higher octane can decrease vehicle performance. Octane rating is simply a measurement of how much heat is required to burn the fuel in the combustion chamber of your car's engine. The engine is tuned specifically to burn the fuel at a certain time, pressure and temperature. If you introduce a fuel which takes longer to burn, then the timing will be off. To compensate for this you would need to retard the ignition timing which may decrease overall performance.

Most people think that higher octane means more power but this is untrue. The amount of energy / heat produced by burning X amount of high octane vs X amount of low octane is the same, only the low octane will burn faster. Putting 92 octane in a vehicle meant for 87 is a waste of money.

The only other argument I have heard is that higher octane gasoline is of higher quality than lower. I don't know whether or not this is true but I can't imagine there would be much of a difference.

 

[Bugeye58]

Jim, take a look here, as this comes up quite frequently.

https://www.britishcarforum.com/ubbthreads/showflat.php?Cat=0&Number=64471&page=&view=&sb=5&o=&fpart=1&vc=1

Jeff