In the early 1970s, he went to Germany to study a football manager grade, finishing it in 1972 at Hamburg. Three years later, Oyarzún joined Lota Schwager, leaving the team amid the tournament. Two seasons later he moved to Deportes Concepción, where despite his short spell was remembered for the incredible performance that the club reached under him as coach alongside the German players Hans Schellberg, Hans Lamour and Ralf Berger. These facts, added his strategy acquired during his years of study at Europe, revolutionized Chilean football.[3]
In 1978, Oyarzún was hired by Chilean giants Universidad de Chile where he re-united with Schellberg, but following bad results he was fired. Months later he joined Ñublense, a first-tier team from Chillán.
Once in Chillán, aged 35 during 1978 as manager of Ñublense, he progressively saw their cancer worsen and died on 10 September.
Hours prior his death at the Herminda Martin Hospital alongside his spouse, his sons and his brother Gastón, he asked the latter to leave him his message to the captain of Carabineros, Fernando Chesta, that he would communicate the team players at the city's Isabel Riquelme Hotel the following:
Tell the team, that if something happens to me tomorrow, that fight with the same heart and desire they had in every game. Tell to Pancho Cuevas that do all the crazy things he knows at the field, that Bonhome play as a tank, that Cerenderos continue being the impassable wall on defense and Aballay run with his seven lungs (...)[2]
The message could not be completely transmitted due to the excitement of the players and the same captain of Carabineros. In the afternoon of that same day, Ñublense played against Colo-Colo and won 2–1 in a memorable match.[2] Once finished the game the players knew that Oyarzún had died; his remains rest in the Municipal Cemetery of Chillán.
