A sealing company came by a week before the sealing job and brushed a
thick black shiny paste on the areas with oil spots. In a few days
the spots were completely gone.

I don't remember if the paste and stains just disappeared or if they
had to be hosed off.

I want to do this myself this year and I cannot locate such a product.
I don't want to call the contractor to ask him! Does anybody know?