Originally Posted by
Chu Chu
The octane rating depends on the test used (e.g. the numbers are different for the same mogas in the U.S. and Europe)
Scale/tests haven't changed.
There are 2 tests and thus 2 number Resesrch and Motor Octane Number (RON and MON)
UDA used the average of the two. That's why the sticker in the pump says (R+M)/2. Also call AKI, anto-knock index
Europe uses just one, RON.
93 AKI (UD) ~ 98 RON (most of the world)