[Steeveedee]

300 series stainless has a high chromium content, which renders the magnetic moment small enough as to be negligible. 400 series stainless has less chromium and as a result is more attracted to a magnet, and will in fact corrode. 300 series stainless does not corrode beyond a boundary layer at the surface of the alloy because of the face-centered cubic structure carrying a layer of oxidized material which does not allow oxygen to penetrate further into the crystalline structure. That's why bumpers are chrome plated.

Nickel is a ferromagnetic metal, and as such is attracted to a magnet just like iron is. Don't take a nickel coin out of your pocket and try a magnet on it, because it is an alloy of copper and nickel, so it's just as much non-magnetic as 300 series stainless. Pure nickel metal is attracted to a magnet just like iron.

If fuel conducted electricity, there wouldn't have to be grounds installed all over the place. The fact that hydrocarbons in general are non-conductors is what drives the requirement for ground straps everywhere, not that it conducts. That's just nonsense. The flow of hydrocarbons generates static electricity precisely because it is a non-conductor. Else why would we be told to ground a container when we fill it at the gas station?