I dont know if there's a benefit to using penetrol at 9.00 a can. It says it's main use is to allow the paint to flow and level better, but that is what the mineral spirits are for. The penetrol does mention adhesion, but it says that it increases adhesion with primers. And I think if you're using mineral spirits, allowing time to dry between coats, and using thin coats, adhesion is not a concern anyways.

Im not saying it would hurt, but I don't know of a benefit of it over mineral spirits for this.