Rabbi Aba says that wine, oil and water comes from one place. Priests take water and oil from the Right and internalize them especially oil that is Chokmah. Oil represents happiness at the beginning and at the end, not like wine that begins with happiness and ends with sadness.
“כַּשֶּׁמֶן הַטּוֹב עַל הָרֹאשׁ יֹרֵד עַל הַזָּקָן זְקַן אַהֲרֹן שֶׁיֹּרֵד עַל פִּי מִדּוֹתָיו”
“It is like the precious oil upon the head, Coming down upon the beard, Aaron’s beard, Coming down upon the edge of his robes.”
Wine that goes to the Left is taken by the Levites that use their voices to sing because wine is never silent. Oil is always in whisper.
He asks; what is the difference between oil and water and answer that oil comes from Chokmah, the thought and always in whisper, without sound and concealed like the thought that is not seen and in a silent state. That is why oil if on the Right.
Wine is never silent because a person who is drunk from wine cannot be quiet. He comes from the Left, Mother, Binah. The Levites that takes the wine sing and raise their voice and in the aspect of judgment of the Left.
“וְנִגְּשׁוּ הַכֹּהֲנִים בְּנֵי לֵוִי כִּי בָם בָּחַר יְהוָה אֱלֹהֶיךָ לְשָׁרְתוֹ וּלְבָרֵךְ בְּשֵׁם יְהוָה וְעַל פִּיהֶם יִהְיֶה כָּל רִיב וְכָל נָגַע”
“Then the priests, the sons of Levi, shall come near, for YHVH your God has chosen them to serve Him and to bless in the name of YHVH; and every dispute and every assault shall be settled by them.”
Moses and Aaron were Levites until God chose Aaron and his descendants to be priests and placed them on the Right column with genetic change. Because they had roots in the Left then can settle the judgments and negativity that may come from the Left.
Daily Zohar # 2699 – Shemini – Aaron's beard