The aluminum VC thread made bring this up. I've tried to clean my stock (TR3) chrome valve cover using regular chrome cleaners and other types of polishing compounds, but it doesn't seem to help. The metal does not seem to be corroded or "broken up" but just sort of stained. I've hesitated to use more harsh abrasives but maybe that's what's needed. Any of you have any suggestions/experience with cleaning these thing up?