Ando, I'd try a mechanical gage to confirm the electric. Oil pressure would be somewhat constant and not just drop off as you state, perhaps a sender or wiring glitch.
I have never seen a filter on a cooling system only a strainer on the intake water line. I also feel "steel wool" would be a very poor choice of material and would only cause flow restrictions.
I'd really like to see a pic of this so called "filter" assembly.
Dave Neptune