He studied with Paul Buck, Hugo Steurer and Wilhelm Kempff. In 1981 he was appointed professor at the Hochschule für Musik und Theater München - the youngest in the history of the institute - where he still teaches. As a soloist he has appeared with many famous conductors and orchestras of the world. In the summer 1977, at the age of 24, Oppitz was the first German to win the Arthur Rubinstein piano competition in Tel Aviv, Israel.
Performance of cycles of complete piano works feature strongly in his concert repertoire, including Schubert's and Grieg's solo piano works, Beethoven's and Mozart's sonatas, Bach's Well-Tempered Clavier, and, especially, the complete works of Johannes Brahms. His recording of the Max Reger Piano Concerto Op. 114 with the Bamberg Symphony Orchestra and conductor Horst Stein is very highly regarded and tops lists of recommended performances of that very challenging work.
In 2009 he received the Brahmspreis from the Brahms Society of Schleswig-Holstein.
Among his students is Valentina Babor.