Leviticus 7:12 NKJV
If he offers it for a thanksgiving, then he shall offer, with the sacrifice of thanksgiving, unleavened cakes mixed with oil, unleavened wafers anointed with oil, or cakes of blended flour mixed with oil.
Those giving a thanksgiving offering had to add oil to it. The oil had to be mixed in.
Spiritual parallel: Just as bread within oil is dry, so is thanksgiving offered to God without the Spirit in it. Jesus said that the time has come for true worshipers to worship the Father in spirit and truth.
Hebrews 13:15 NKJV says, "Therefore by Him let us continually offer the sacrifice of praise to God, that is, the fruit of our lips, giving thanks to His name."
Paul said in 1 Corinthians 14:16-17 that we give thanks well when we do it with our spirits by the power of the Holy Spirit. Our praise should not be ritualistic. It should be anointed. Sometimes we may need to put one hand on our belly when we praise with our understanding to remind ourselves to mix that praise with oil. When we praise with the spirit it is automatically anointed.