He started his academic career teaching Classics at Northwestern University, and studying deeply in important German scholarship.

Oldfather was strongly influenced by his studies in Germany: he became a great admirer of German scholarship, nearly bilingual in the language, and sympathetic to the Socialist cause.

"[5] Insisting on a public meeting at the university, Oldfather and his colleagues were exonerated but most of them did not have positions equivalent to his and were dismissed, part of widespread discrimination against German-associated persons during the war.

[5] After the war, Oldfather worked to re-establish connections with German scholars and support major projects in classical studies.

From 1915 Oldfather also served as chief editor of a monograph series, Illinois Studies in Languages and Literature, and, from 1931, as curator of the classical museum.

Oldfather observed that German scholarship in the classics interrogated the past on significant issues related to the problems of politics and economics that recur in modern life.

Late one Sunday afternoon in May 1945 he attempted to shoot his canoe over a knee-high dam in the Salt Fork River near Homer, Illinois.