If you have oil on the surface, I would clean it with lacquer thinner. Water rinse is not necessary in my experience, nor is neutralizing.
Some suppliers of metal preparations reccommend rinseing with water, but you get almost immediate flash rust unless you can immediately dry the surface. If you have seams that water can get in, your asking for rust, IMO.
I spray phosphoric acid solution on surface and let it sit a few minutes then scub with a scotch brite pad and wipe up the dirty solution. Repeat as long as your removing rust. If the surface has stubbord rust pits, I use a stiff wire brush on a 4 1/2 inch grinder to scuff the pits and repeat the acid wash as many times as necessary to clean the metal.
If you let the solution puddle and dry on the surface you will get a black residue, but its easy to remove with another application of acid solution.
When I'm finished working on the metal for the day, I spray on the solution and immediately wipe it up so the surface is dry, which leaves it clean and protected from rusting as long as its kept dry.
