In light of this, we can understand the choice of oil as a metaphor for Chassidus. Oil has two distinctive qualities: it does not mix with any other liquid and it can penetrate all matter. The same is true of the teachings of Chabad Chassidism. It reveals the essence of our souls, the highest of our potentials. The Alter Rebbe's contribution enables this potential to influence and affect the functioning of all our powers, and thus be expressed in every aspect of our lives.

The Rebbe - On the Essence of Chassidus