Sorry, yes, you are correct, it is indeed steering wheel and not whell. It was due to fast typing and quick replying. What I mean with the steering wheel shine is about the wear of the material (usually leather)
I'm not a specialist but view it as a mix of diferent things and not just an isolated factor (sweat, hand cream, dry hands, natural oils, etc.), and depends on so much variables, for example how hard one grabs it, how one positions the hands and even the cleaning regime and products influence it. I personally hate the shiny steering wheels and do what I can to avoid it but, from my experience, even at 5,000kms there are signs of wear.