I am painting an old work truck for a friend and it has been painted several times with who knows what. He wants just a ok job for this farm truck but doesn't want the paint to fall off. What would be a good first product before paint? I always seal every job but was thinking about some slick sand or feather fill ? I am looking just for a good foundation for my paint to bond to. I know everyone will say sand it all off and then prime but this is a $200 paint job including paint so I can't spend 100 hrs on prep. Please just give me your opinions. Thanks in advance.