Three weeks of wiping down my dash with the wrong stuff, and I finally saw what it did
I picked up a '65 Impala back in April and the dash pad looked fine when I got it. Started using a cheap dressing on it every couple weeks because that is what I had in the garage, and about a month in I noticed the surface going shiny and a little tacky in the sun. Switched to plain mild soap and water with a soft rag and after three weeks the dull finish came back and the tackiness is gone. Turns out the stuff I was using was pulling something out of the vinyl, or at least that is how it looked to me. Anyone else run into this on old dash pads, and what are you using instead?
Went through the exact same thing with a 66 Malibu and that greasy shine drove me nuts for weeks. The old vinyl just soaks up whatever you put on it and gives it right back when the sun hits, so plain soap and water is really all those pads ever needed. Keep doing what you are doing and that dull factory look will stick around a lot longer.