First and Second Maccabees, written within a generation or two of the events of 164 BCE and the closest surviving sources to them, describe the rededication of the Temple and the establishment of an eight day festival in detail, but neither mentions any oil lasting beyond its measure. Second Maccabees instead explains the eight days as a delayed celebration of Sukkot, the harvest festival the fighters had been unable to observe properly while occupying the Temple. The historian Josephus, writing in the first century CE and closer in time to the Talmud's editors than to the Maccabees, also describes the festival, which he calls the Festival of Lights, without telling the oil story either.
Scholars of Second Temple and rabbinic Judaism, including Shaye Cohen, read this silence as evidence that the oil story is a later rabbinic elaboration rather than part of the earliest layer of Hanukkah tradition, composed or preserved by the rabbis of the Talmudic period for their own reasons, centuries after the fact. Whether the rabbis invented the story outright or drew on an oral tradition that had simply gone unrecorded in the earlier written sources is not something the surviving evidence can settle either way.
Sources First and Second MaccabeesAnonymous with From the Maccabees to the MishnahShaye J. D. Cohen