Are careless tenants responsible if the cast iron griddle & grates (on stove) rust?

[Trevor Justice]

I just replaced my 19 year old gas range with a new one, only to realize that its griddle & grates are cast iron. If not cleaned well, dried, and oiled regularly, cast iron can rust. If in a lease, tenants agree to properly care for the griddle & grates, but then they don't, can they still argue that rust is "normal wear and tear"? Note that I'm in Oakland CA where judges are known to side with tenants.