Oil -- typically olive oil -- symbolizes the good that comes from celestial love. Celestial love is love of the Lord, the highest and purest love we can have. The good of celestial love is the desire to be good springing from celestial love: Wanting to do the Lord's will because you love Him. That's not a state many reach, even in heaven, but it's a beautiful goal. This representation makes sense based on the idea that the sun -- the source of all natural light and heat, and thus all natural life -- represents the Lord, the source of all spiritual light, heat and life. Burning oil was the most pure fire available in Biblical times, thus the closest representation of the sun people could create.

9399. 'And Moses took the blood, and sprinkled it over the people' means making a person well-adapted to receive it. This is clear from the meaning of 'the blood of the sacrifice' as Divine Truth emanating from the Lord, dealt with above in 9393; and from the meaning of 'sprinkling over the people' as making a person well-adapted to receive it, for 'sprinkling' means flowing into something, that is, adapting it. Divine Truth which emanates from the Lord is flowing unceasingly into a person and composing his understanding; indeed, if you are willing to believe it, without that unceasing inflow of God's truth emanating from the Lord he can see and learn nothing. For the Divine Truth emanating from the Lord is the light which enlightens the human mind and composes inner sight, which is the understanding. And since that light flows in unceasingly, it makes every person well-adapted to receive it. Those who do receive it however are people who lead a good life, whereas those who do not receive it are people who lead a bad life. Even so, the latter have the ability, just as the former do, to see and learn Divine Truth, and also to receive it to the extent that they depart from evil ways. This is what the half of the blood sprinkled over the people by Moses served to mean.

[2] Regarding Divine Truth emanating from the Lord, that it is the Light which enlightens the human mind and composes its inner sight, which is the understanding, see 2776, 3167, 3195, 3636, 3643, 3993, 4405, 5400, 8644, 8707.

This Divine Truth is also meant in John,

He was the true light which enlightens every person coming into the world. He was in the world, and the world was made by Him, but the world did not know Him. John 1:9-11.

This refers to the Word, which is Divine Truth emanating from the Lord.

[3] Every person in the world who is sound in mind has the ability to learn God's truth, and consequently has the ability to receive it to the extent that he departs from evil ways, as considerable experience has enabled me to know. For all without exception in the next life, the evil as well as the good, are able to learn what is true and what is false, also what is good and what is bad. But the evil, though they can see what truth or good is, have no wish to see it; for their will, and the evil there, finds it repugnant. When left alone to themselves therefore the evil fall back to the falsities accompanying their evil, in detestation of the truth or good they have come to see. The same applied to such people when they were in the world, where they refused to accept truths which they were able to see. From this it has been evident to me that Divine Truth emanating from the Lord flows constantly into human minds and makes them well-adapted to receive it, and that it is indeed received by people to the extent that they depart from the evil ways that go with self-love and love of the world.