I do this;
- Blast super clean with very light media
- Air blast off any residue, while working the hinge (wearing gloves or holding with a clean rag)
- wax and grease remover
- soak in fresh phosphoric acid solution for anywhere from 30 minutes to 2 hours
- remove and immediately air balst completely dry
- hit with penetrating oil (I use Penetrene, WD40 can be used in a pinch but it does nto work real well long term in my experience)
I have tried a few nuts and bold in hot motor oil, new multi-vis to just below smoking point, and it works OK. Do not see much difference to the "cold" method. Have been considering an electric thermostat controlled hot plate and big stainless pan for this but have not tried it, have heard the heated phosphoric process works a bit better.
The will eventually rust again. Regular maintenance with more Penetrene can keep it at bay, but hard to do without taking them off or getting a bit of a mess under the hood...
Some examples of nuts and bolts I have done here...
http://www.mustang.org.au/forum/index.php/topic,24299.0.html
Marty is it the T-9 that you use? I can pick up a 12 oz spray can for $35 here...