Oyu, fresh from scoring his first ever Super Formula pole last time out at Motegi, set his best time of 1m37.487s with around 15 minutes left on the clock in the 90-minute session on Friday afternoon.
That put him a comfortable 0.342 seconds clear of his nearest rival, Inging driver Sho Tsuboi, who led a flurry of improvements at the end of what proved to be an incident-free session.
