I Need your advice. I am from the old school and have using OSPHO on my projects for years. I would sand the bare metal down that I applied it to and then prime. With all the new types of paint these days, I am told that you should not or can not put etch primer on top of OSPHO. I was told to use a wash primer on top of sanded bare metal that has been treated with OSPHO, such as Dupont 5717s and 5718s and then prime with apoxy primer before begining body work. What exactly is wash primer? I was also shown a product from NAPA that is called Rust extender? that when applied turns the rust black along with your skin if it gets on it. Any thoughts on this anyone?

Your questions are wide with debate. First off, without a doubt you do NOT want to apply any "wash" primer (a high acid type of etch primer) or any etch primer over a metal treated with OSPHO, 5718S, 5717S or any other product without TOTALLY following the tech sheet. OSPHO leaves a phosphoric coating on the metal that the acid in the etch can attack leaving you with next to no adheasion. The etch or wash primer REPLACES the need for the metal treatment, that is the whole idea.

DO NOT use the "Rust extender" it is a "magic potion" in my humble opinion.
There are plenty of REAL products by the paint manufactures to protect your metal. Clean the rust out instead of covering it. Now, if you need to clean it out with some sort of conditioner like OSPHO, fine. But if you are not using a product that is a PART OF a system like 5718S and has recommendations of what primers to follow, you are REALLLLLLY taking a chance.