输油 is a verb-object compound (离合词) meaning 'to transport oil' — usually oil or petroleum through pipelines or tankers. As a separable verb, you can insert measure words or time expressions between the two characters, e.g., 输了一次油 ('transported oil once'). The object 油 cannot take a separate object after the whole word; instead, the location or method is expressed with prepositions like 通过 or 从.