Many years ago, I looked at using some of this stuff since track prep at these little tracks was about nonexistent. Super Stock guy I know had sent off some of the tire softener available at the time to be checked. His brother worked at a high end race shop and had access to a lab.

Diesel fuel and WD40. So me being the experimenter, I give my tires a good painting of straight diesel fuel and leave them sit for a few days. Made sense, knowing how tires are made.

Actually helped, but only for a few runs. Went away pretty quick. I didn't experiment with mixing WD but have to assume that would have made the diesel penetrate deeper.