This is a test of a commercial deruster called Evapo-rust

Moderately rusty cold rolled steel bar. No oily spots. Even layer of rust, slight pitting. 
I applied the solution with a piece of 0000 steel wool, with a very light scouring action, 
just the weight of my hand, mostly to keep the solution on top of the round bar.

The process went like this: 
Applied the solution for about 30 sec, 
Let it sit for a couple of minutes, 
Applied fresh solution for another 30 sec, 
Wiped it off with a damp rag, 
Wiped with a patch wetted with Evap-orust to retard rusting. 

The rust is completely gone in all but the deepest pits. 
No elbow grease 
No rerusting 
No grit left behind

I am in no way associated with the company, just very impressed

Paul K. Dickman