Hello Bama31,
I'm guessing that a petroleum product may have been used for a number of reasons. Moisture proofing corrosion control, seam sealing, sound deadening, maybe? If you want to add-to and clean-up the area that your working, you might re-coat with automotive undercoating/bed liner/sealer type products. Something that the smell goes away when dry. Or maybe, the peel and stick sound proofing products made for automobiles. Some have reflective foil some don't. It's pretty much up to what you're looking to accomplish.
