Oil pressure idiot light stays on

It won't go off? It must sense an idiot :D...lol (jk)

I use nylon all the time. You can buy small grommets to pass it through the sheetmetal, and unless you melt it or cut it, I've never had one fail or burst on it's own. That's running them since 1986. Copper will work, but you will also notice a ton of movement in the needle as the tubing tends to remove the myriad of pulses that the oiling system normally experiences. I've never seen copper break either, but it never came in the gage pkg so I used what was provided.