Some paint brands will not work with Ospho unless it is neutralized—those brands will clearly state it in their instruction sheets. The local autobody paint shop will be aware of which ones need it. MINE I bought did not need it…but Ospho left a gummy black on the body panels, and so I elected to neutralize it anyway to get rid of the sticky goo. That goo can cause the paint to bubble. There are many threads on this noted on the web.
If you look at the OSPHO instructions Gary shared, you will see that Ospho recommends some sort of cleaning after whether that is by mineral spirits or soapy water—that is essentially neutralizing.
How for the frame and powder coating, or some other paint restore for that, there may be no neutralization needed. For body paint, I would absolutely neutralize, espcially if Ospho does not turn to a white powder, and instead leave a black gooey residue.
Thanks for the info, I picked up some Ospho this week to try out on the frame, It did turn black and gooey so im going to clean it as much as possible, However haven't ordered my Chasis saver paint yet. On an unrelated note, does anyone know if a steering stabilizer was standard on the dana 44hds? I just noticed it had one while ive been removing the front end over the last few days. will have some more updated pictures once I get this last pesky core support bolt out tonight after work.