I have use Krylon short cuts flat black for years on chassis and interiors never a problem. I like that it dries to a almost satin finish. If I use Rustoleum it’s a satin and not the primer and paint all in one. The Rustoleum I have is in short cans called American Accents not made any more. I rarely use my old Rustoliun. I use Tamiya paint and primer mostly.