The owner's manual states Regular Unleaded gasoline (Gasohol E10 acceptable). However, the Vehicle Emission Control Information label specifies 91 RON (Research Octane Number). This may be confusing as regular gas has the posted pump octane number 87 (pump octane is the average of RON + MON). In general, RON values are never less than MON (Motor Octane Number) so 87 pump octane could meet emission specs. In riding practice, if you don't hear pinging or knock under acceleration, regular should be OK.