The thing that marks the foolish virgins from the wise....The foolish didn't take oil with their lamps, the wise did.
Oil in the Bible is a type of the Holy Spirit.
...............The oil of the Holy Spirit is contained in vessels, our bodies, which are temple of the Holy Spirit.
..........The foolish virgins may have had oil in their vessels, at the beginning, since their lamps had burned for a while; but they failed to replenish their supply.