It is very important that you season or cure your new BBQ plate to stop it from rusting.

Get some vegetable oil or vegetable oil spray and cover the BBQ plate, grill etc with the oil.  Cover all of the cast iron surfaces for the best result.

Turn your BBQ on and heat it until the oil starts to smoke on the plate (if you have a hooded BBQ leave the lid open).

Turn down your BBQ and using some water and a stiff wire brush and some crunched up newspaper, scrub the plates clean.

Turn the BBQ off at the bottle (if it is a gas BBQ) and then off at the controls.  Cover the cast iron plates and parts with a light layer of vegetable oil or spray.

Your barbecue is now good to go!