«Dear Rabbi Wolpoe,
Thank you for contacting the OU.
Yes, even grates placed in the oven will get kashered. The self clean cycle usually lasts between 2-4 hours this is long enough that we can assume that everything put in the oven will get hot enough. This is a kashering for treif and for Pesach. Metal begins to glow at about 400 C and already at 500 C is quite visible.
400 C -- 752 F-- Red heat, visible in the dark
474 C -- 885 F-- Red heat, visible in the twilight
525 C -- 975 F-- Red heat, visible in the daylight
Note: valid for Passover 2014 only»
I could not have said it better.