one of my friend in australia told me that they have 91,95,98 and 100 octane gas in Australia,and they said even China they got 98octane gas, but how come US only got 92 89 and 87? I told them about that,they thought I was joking...

 

We have low grade fuel here because environmentalist incorrectly believe a lousy running car will clean up the pollution. The liberal states tend to have only 91 and the conserv states tend to have 93 - in most cases.

I just could care less - run methanol inj

 

it has diff ratings the ones in australia 91ron=87mon, 95ron=91mon, 98ron=93mon, 100ron=95mon.
mon is for USA

 

USA uses (RON+MON)/2. Other countries use either RON or MON alone- I can't remember which.