Strickly speaking the runway names are names and not headings. For
example at Denver, runway 16L is 170 degrees magnetic due to their
being a runway 17L and R already with the same magnetic heading.

As for the runway 8 or zero 8, it seems to be always written 8 and not
08, but I don't think it is a big error, though apparently some pilots
are being taught this way, because you do hear it.