Are the stock rotors cast iron? My rotors get the rusty look after washing the car and it sits a while.

 

They are cast, but I seriously doubt that it is iron. More likely a steel alloy. ALL steel will rust unless treated with some kind of plating or chemical immersion, especially if left sitting wet. In drier climates it is less and in wetter climates it is worse. I live in Oregon and things do rust if left uncared for. I recently took off a set of factory rotors and replaced with PowerDisc slotted rotors and the factory ones still looked VERY good with 23000 miles on them. All the non working surfaces have rust on them but that dosent hurt the life or performance of the rotor. It just dosent look nice.

MikeR

 

I have never owned a car that didn't have brakes that rusted after washing...totally normal.

 

Yup, same here!
Worry not, they'll be fine. If you let the car sit for a couple months (like during winter) then I'd be a wee bit more concerned 'cause the rotors will pit.