Its three principal uses among the Hebrew were:
(1) To anoint the body so as to mollify the skin, heal injuries, and strengthen muscles (Psalm 104:15; Psalm 109:18; Psalm 141:5; Isaiah 1:6; Luke 10:34; 2 Chronicles 28:15; Mark 6:13; James 5:14) (See ANOINT.)
(2) As we use butter, as food (Numbers 11:8; 1 Kings 17:12; 1 Chronicles 12:40; Ezekiel 16:13; Ezekiel 16:19; Hosea 2:5).
(3) To burn in lamps (Exodus 25:6; Matthew 25:3).
Type of the Holy Spirit's unction (2 Corinthians 1:21; 1 John 2:20; 1 John 2:27) and illumination (Zechariah 4:11-12). The supply of grace comes not from a dead reservoir of oil, but through living "olive trees." Ordinances and ministers are channels, not the grace itself; Zechariah 4:14, "anointed ones," Hebrew sons of oil; Isaiah 5:1, "very fruitful hill," Hebrew "horn of the son of oil." The Lord Jesus has the fullness of grace from the double olive tree of the Holy Spirit, so as to be at once our priest and king; He is the tree, ministers the branches, "emptying the golden oil out of themselves" for the supply of the church and to the glory of the Author of grace. In the sanctuary oil served the three purposes:
(1) anointing the priests and holy things,
(2) as food in the bloodless offerings (minchah),
(3) it kept alive the lights in "the pure candlestick," "the lamp of God" (1 Samuel 3:3) in the holy place.
Messiah is the Antitype "anointed with the oil of gladness above His fellows" (Hebrews 1:9; Psalm 45:7); not only above us, the adopted members of God's family, but above the angels, partakers with Him, though infinitely His inferiors, in the holiness and joys of heaven. His anointing with "the oil of exulting joy" took place not at His baptism when He began His ministry for us, but at His triumphant completion of His work, at His ascension (Ephesians 4:8; Psalm 68:18), when He obtained the Holy Spirit without measure (John 3:34), to impart to us in measure. The oil of gladness shall be in the fullest sense His "in the day of His espousals, in the day of the gladness of His heart" (Song of Solomon 3:11; Revelation 19:7). Guests were anointed with oil at feasts; so He anoints us, Psalm 23:5.
The offering of oil on the altar was the offerer's acknowledgment that all his spiritual gifts were from Jehovah. The "beaten oil" for the sanctuary light was made from olives bruised in a mortar. So Messiah's bruising preceded His pouring out the Spirit on us (Exodus 25:6; Exodus 27:20). The olives were sometimes "trodden" (Micah 6:15), or "pressed" in a "press," making the fats overflow (Joel 2:24; Joel 3:13; Haggai 2:16). The oil was stored in cellars, in cruses (1 Kings 17:14). Solomon supplied Hiram with "20,000 baths of oil" (2 Chronicles 2:10), "20 measures of pure oil" (1 Kings 5:11). Oil was exported to Egypt as the special produce of Israel (Hosea 12:1). Meat offerings were mingled or anointed with oil (Leviticus 7:10; Leviticus 7:12); but the sin offering and the offering of jealousy were without oil (Leviticus 5:11; Numbers 5:15). The oil indicated" gladness"; its absence sorrow and humiliation (Isaiah 61:3; Joel 2:19; Psalm 45:7).
Fausset, Andrew Robert M.A., D.D., "Definition for 'oil' Fausset's Bible Dictionary".