Just filled up the tank with 91 octane premium fuel

[07WYarisRS]

Originally Posted by DerFlosser

higher octane fuel is a cleaner ignition assuming you have a healthy ignition system (all components). Other than than...one would really be hard pressed to tell the difference between an 89 and a 91 in a Yaris. It's a low-mid compression motor with 100hp. I can possibly see smoother starts but as far as running and gas mileage....we all know that the higher octane provides no benefits.

Higher octane does NOT have a cleaner ignition
Unless the compression is high enough to take ad vantage of the fuels flash point, burn rates and flame front speeds the engine will not burn as efficiently a a low octane and you end up with carbon deposits.
Lower octane fuels burn cleaner and more efficiently in ANY lower compression engines.
but I just build performance engines for a living and actually test them using the proper equipment..WTF would I know about fuels and the affects right?

Don't confuse RON and PON people
A 89 RON octane rating is PON (pump octane rating) of 86
when you look in the manual and see a research octane rating of 91 that does not mean to use 91 pumop octane... 91 RON = 87 PON.
Toyota, Honda and most other companies build thier econo engine to run on RON 89 (pump octane 86) because thats whats all thats available in some counties for low octane and it makes these engines most cost effective...

I'll never understand people that buy one of the cheapest econo boxes on the market and then run it on high octane ... you guys are nuts lol
you guys much know more then the dudes in white lab coats at toyota