how high an octane is too high?

[raverboy]

I was curious as to wheather or not high octane damages a catalytic converter. My auto teacher told me that it does but I was wondering if there was limit that a cat can handle before damage is done. For instance, can the cat handle 100 octane before any of the internals are destroyed?

 

[JKGMotosports]

92-100 Octane wont do any damage, it burns cleaner which is better in the long run.

 

[GILZTSIAWD]

Certain high octanes that are leaded will harm your emissions equipment even including your o2 sensors. Some even say that the leaded gas can clog up injectors and mess other things up. I think your auto teacher was referring to the higher octane gas around 114 i believe it is where the gas starts only coming in the leaded form.

 

[Defiant]

Christ, shop teachers.
Octane comes from additives, which don't burn as well nor as cleanly as gasoline. From that end of it, yes, there's more ash and solid by-product left from the burning of higher-octane fuel, but not to the extent that a cataclysmic diverter will be impacted by it. What does have a detrimental effect on cats is leaded gasoline, as the lead salts can coat the catalyzing agents in some styles of convertors and greatly reduce their effectiveness. However, it seems that returning to unleaded gas burns these deposits off after a few tanks.
I've heard no mention of any unleaded gasoline having a deleterious effect on convertors. If you have something saying differently, I'm keen to see it.

 

[Defiant]

92-100 Octane wont do any damage, it burns cleaner which is better in the long run.

Not true. Higher octane has more junk in it to burn (and, to retard burning) and leaves more deposits. For any motor, you want to run as low an octane rating as the design will allow.

 

[femmeDSM]

Not true. Higher octane has more junk in it to burn (and, to retard burning) and leaves more deposits. For any motor, you want to run as low an octane rating as the design will allow.

Thank you, I was about to say the exact same thing.
You beat me to it.
If your car doesn't knock/ping on 91 octane, then don't use 93. .... and so on. No reason for it, other than wasting money. But if you're like my old GS-T that knocked like a b*tch on 93 octane and had to use commercial additives, then you have a problem. .