Primarily Petroliana Shop Talk Forums Shop Talk Petroliana Forums General Petroliana Discussion Problem with gunk on steel computer cover

So here is the top cover for my computer. Its basically a thin steel sheet. I have this gunk thats on it which resembles a cross between gas sludge, sandpaper and mold. It feels rough like sandpaper, looks like mold and won't come off like sludge.
Anyone have experience removing this???
So far I have tried various chemicals, soaking in vinegar, metal and vinyl brushes, etc. May try a polishing wheel on a bench grinder but don't think itll help much.

Any suggestions?