Advice for seasoning cast iron cooking grid

kmcadillac44

I use the T-rex method every weekend to do a couple of steaks (I put the cast iron grid on top of the reducer ring so that is basically sits on the charcoal when I sear the steak).  I then leave it in place and put the normal grid in for the 400 degree portion og the cook).  After two years the cast iron grid has rusted so badly it is more of less disintegrating.

Are there any methods to make my new on elast longer (just bought a 15 inch from BGE)