from the customs of the time --

"Cruise of oil --

A small jar with a rounded bottom, at hand in every house in case of going out at night to a neighbor´s house. The little lamp soon consumes what it contains, and it would be necessary to replenish it before returning home. The light of a lamp is not extinguished; it would be left burning during the visit, if its oil permitted. The cruise contains a supply to replenish the lamp. The foolish virgins were unwise to go out without their cruise of oil."

"The wedding procession --

The bridegroom set out with the bride from the house of her parents, and there followed a grand procession all the way to his house. The streets of Asiatic cities were dark, and it was necessary that anybody venturing forth at night should carry a lamp or torch. Those invited guests, who did not go to the bride´s home were allowed to join the procession along the way, and go with the whole group to the marriage feast. Without a torch or lamp they couldn´t join the procession, or enter the bridegroom´s house.
The ten virgins waited for the procession to arrive at the point where they were waiting; and five wise ones were able to proceed because they had a reserve supply of oil for their lamps; but the foolish virgins lacked that oil and so, not being ready, they were barred from the wedding feast."

Sounds like the Holy Spirit to me. If Jesus and His Church are on the way to the wedding feast; the only people who would be waiting for Him would be the Jews. Those devout Jews who waited for the messiah, and would have sought out the Holy Spirit (or God) would be prepared; but those Jews who believed in God (they did have a light for awhile) but weren´t expecting the messiah, would suddenly try to join the Church (but after the Rapture wouldn´t find anyone to lead them to Christ in time); would miss out.

IMO -- this one is deep. Probably multiple meanings.