I know some countries have different ratings, i can't remember exactly but im sure there are three. Ron mon and some other one. I think 95 in Australia is similar to 89 in America.
I also consistently use bp 98
This interested me so as it's raining outside I decided to do a quick search. Good old Wiki came up with the best explanation as to why we are all using different numbers around the world.
"Anti-Knock Index (AKI) or (R+M)/2[edit]
In most countries, including Australia, New Zealand and all of those in Europe,[citation needed] the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2). It may also sometimes be called the Posted Octane Number (PON).
Difference between RON, MON, and AKI[edit]
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. This difference between RON and MON is known as the fuel's Sensitivity,[4] and is not typically published for those countries that use the Anti-Knock Index labelling system."
Another interesting point ,I haven't copied, is some manufacturers change their fuel dependant on time of year or altitude so they have a more consistent burn across a wider range of variables:nerd: