Raced an RA41 125cc factory machine in the Isle of Man TT GP125, the second round of Yamaha's first GP in 1961, where he came 12th, one place after Fumio Ito (11th). A race rider who was also an employee of Yamaha Motor, Oishi raced in the GP while also testing Yamaha's production machines. After retiring from Yamaha, he moved to Prince, which was to later merge with Nissan, and participated in numerous automobile race events.
|Year||Class||Result & Pole position||Machine|
|1961||125cc||no point||PP: 0||1st: 0||2nd: 0||3rd: 0||RA41|
*Results for years with a Yamaha factory team, riding a Yamaha factory machine or ranked 5th or higher riding a Yamaha production racer (World GP, World F750)