There’s two primary ways to measure octane. RON and MON. Most countries pick one- specifically RON. The US and Canada average the two, for some reason.
In Canada, The United States, and Mexico, the advertised octane rating is the average of the RON and the MON, called the Anti-Knock Index (AKI). It is often written on pumps as (R+M)/2. AKI is also sometimes called PON (Pump Octane Number).
Because of the 8 to 12 octane number difference between RON and MON noted above, the AKI shown in Canada and the United States is 4 to 6 octane numbers lower than elsewhere in the world for the same fuel.
There’s a table in the wiki article that shows the equivalence of different systems
Huh, how does the octane rating work in the US?
Common octane ratings in NZ are 91, 95, & 98.
I’m guessing that there are different ways to calculate the rating, rather than the actual fuel being that different.
There’s two primary ways to measure octane. RON and MON. Most countries pick one- specifically RON. The US and Canada average the two, for some reason.
Yes. USA, Canada and Mexico use a different rating. You need to add about 5 to get the same number on the more common RON scale.
There’s a table in the wiki article that shows the equivalence of different systems
https://en.wikipedia.org/wiki/Octane_rating
That was quite informative, thanks. I’d always wondered about the specifics and had never remembered to look it up.