i haven't seen this yet in the M3's I have driven on the ring however the cars usually sit for several minutes in the car park in between. my problem is the brakes fade at about mid-way through the 2nd continuous lap. cooling is always a good idea. i think the secondary oil cooler would help more than just the power steering pump. also boiling fluid no matter what it is can't be good!
"It gave you amazing satisfaction, but anyone who says he loved it is either a liar or he wasn't going fast enough." - Jackie Stewart on racing at the Nurburgring