Whatever you do please do not use anything less than 91 octain.
reason being is higher octain detonated much later than low octain. and an engine designed for high octain runs more eficient on just that, higher octain fuel.
lower octain has more impurities therfore more burning capabilities and a earlier detonation point. higher octain engines have a later detonation point of combustion rating hence a higher compression point of detionation.
using a lower octain will not only cause pinging, but unwanted, early engine power robbing, detonations. [PHEW]