Tama, follow the recommended octane by the manufacturer.

Although has 9.6:1 lang ang ratio nitong Nissan 240SX 1993 DOHC 16V ko, nakalagay sa may odometer "Unleaded Fuel Only." Pero pag tinignan mo sa owners manual and gas gap: Premium Octane (91 Octane in California) is highly recommended for maximum performance. Nagkarga ako ng 87 one time, it takes a while to accelerate. Matagal na akong nakatapak sa gas, pero ambagal ng acceleration. I figured, if it takes me a while to accelerate, I will end up consuming more gas. Wala namang knock pero ambagal lang mag accelerate. 87 Octane yata ang last resort kung walang premium para sa tsikot na to.