 He won a bronze medal in the 4 × 10 km relay at the 1968 Winter Olympics in Grenoble and placed seventh in the 30 km event at those same games.Oikarainen's biggest success was at the FIS Nordic World Ski Championships, where earned a gold in 50 km in 1970 and a silver in the 4 × 10 km relay in 1966.He also won the 15 km event at the 1959 Holmenkollen ski festival.