Ok so I am just about to hit 36,000. and my brake wear light indicator comes on. It comes on every time I hit to brake. So i figured its about time to change. My friend and BMW junkie is going to help me change my pads, and possibly paint my calipers. He is practiclly insisting we change the rotors, or have them milled down to spec when we change pads. He says its useless to change pads without rotors being milled down. Do i really need to? Any thing i need to be aware of when change brakes myself?