That's BS :thumbsdown: . As per BMW AG - TIS 17.03.2005 00:46

Max. machining limit per friction ring side (M models must not be machined!) mm 0.8

 

Find an independent BMW auto shop for rotor resurfacing. Make sure thickness after resurfacing is not less than MIN TH stamped on brake rotor.

 

you should just have to rotate them, unless they are really worn down.

 

while we are on the topic of brakes,

if my car stops well and pedal feels nice and firm is it important to change the brake fuild every 2 years like the idrive tells me to?

or can i go until i need new pads to do that as well?

 

+1 Always a good idea to turn rotors when installing new pads. Removes the glaze and makes them true.

 

Brake fluid attracts moisture(hygroscopic), and this moisture can rust the insides of the brake system, and also lowers brake fluid boiling point. This moisture was not that big of deal 10 years ago, but on ABS brake systems, the rust and other debris that accumulates in the fluid can do lots of internal damage, and can be very costly. Brake fluid can also break down over time from excess heat that is created from within the brake system. I flush mine at least once a year because it's easy and for peace of mind.