Cleaning vinyl

I have been reading a restoration book on classic cars. It said to use goop, or go-jo hand cleaner to clean vinyl seats. It said to apply it all over the seats using a nylon brush. Now sprinkle a very tiny bit of water and rub some more to lift the dirt from the seat. Less water is cleaning more it says. After this clean the seat with clean water, dry and put in the sun to dry. The article said this would clean and also soften the seats better than anything else.
Just curious, as of now all I have been able to do is read and collect the needed parts to finish my 4+ year project.
Any thoughts, or has anyone tried this. You know the vinyl in a 50 year old rear seat is hard and brittle. I am replacing the front seat covers but was trying to use the back after cleaning. I know, I'm being cheap here.
Thanks as usual