rootboy 

Thanks Frank. I'll bet it's nickel, from the looks of it, but of course chrome can get that look when it's old and worn. Nickel has that sort of warmish glow, as you know.

Wasn't sure you were referring to an actual oil cap in a previous post or not. Sounds like the ones on the old British bikes were actual oilers, with a spring-loaded, hinged cap, etc. While the one on the Italian bike looks more like a grease zerk, though I understand it was meant for oil as well.