An Etymological Dictionary of the German Language/Öl
Öl, n., from the equiv. MidHG. öle, öl, n. (with the variants ole, ol, and olei), OHG. olei, oli, n., ‘oil’; corresponding to OSax. olig; Du. olie, AS. ele, n., ‘oil.’ Lat. oleum, ‘oil,’ passed into HG. before the 8th. cent. Goth. adopted the term probably even half a century earlier from the Lat., the only assumption that can explain the remarkable Goth. form alêw. The approximate source of E. oil, MidE. oile, is OFr. oil, which with its Rom. cognates. (ModFr. huile) are also based on Lat. oleum.