The tC manual states Research Octane Number 91 for gasoline requirements. Whats the difference between Octane Rating 87 and Research Octane Number 91?

 

tC gas is 91? are you serious Ive been driving with 87 when I got it

 

It says, "Select Octane Rating 87 (Research Octane Number 91) or higher.

Funny thing, like Chevron, Techron gasoline. ron = (Research Octane Number)

 

"Research Octane" is just one of two numbers used to determine "pump octane".

If you look at the gas pump, under the octane number it should say "Determined by the (R+M)/2 method". The "R" in the formula is the "Research Octane Number", the "M" is the "Motor Octane Number".

So if it says that to use 91 RON the MON would be at 83 hence (91 RON + 83 MON)/2 = 87 Pump Octane

Hope this cleared up any confusion.