Ordinary שמן (oil) means olive oil. And when it is written with respect to the Menorah, שמן זית (olive oil)⁷³⁹, there is a homiletical interpretation.

footnotes: ⁷³⁹ Leviticus 24:2.

And ordinary שמן that is mentioned with respect to thanksgiving offerings⁷⁴⁰ is a log (a Biblical measure of liquid volume).

When the Torah saysשמן זית*(olive oil) with respect to the Menorah, the wordזית(olive) is superfluous, since according to Rule 549, even if the Torah only had saidשמן, it would still mean olive oil. The homiletical interpretation is that the extra wordזיתis there to indicate that the olives should be so ripe that oil drips from them while they are still attached to the tree⁷⁴¹.*

footnotes: ⁷⁴⁰ Leviticus 7:12. ⁷⁴¹ Malbim, HaTorah v’HaMitzvah Emor 210.