I struggled for years with liquid strippers. The problem is they run off the surface or evaporate, it's never on the paint long enough to get the work done. A much easier way is to use a gell. You paint the gell on with a brush and leave it. It doesn't run off or evaporate. The longer you leave it on, the deeper it goes. You can take it off with a plastic putty knife, rag, or steel wool, all depends on how deep you want to go. My wife has been refinishing furniture for years, always using a product called CitriStrip Gel. It removes anything, latex or oil-based paint, varnish, or shellac. It's sold at any home improvement or hardware store for about $15 a bottle. It doesn't smell, has no harmful fumes, creates no heat, and can be used indoors. I have to credit her with the idea, I never thought to try it on car paint. It's a huge time saver.