I still use an old pot of Mithril Silver for extreme highlights on silvery and gold metal surfaces. I also have the Vallejo Game Color variant, which is simply called Silver IIRC.
When I want things overall shinier, I tend to start a step up from Oily Steel; Gunmetal, then on to the one above (the name eludes me right now) and finally the aforementioned silver. All of the above are Vallejo Game Colors btw.
Hope that helps...