Another fan of oil temp over water temp here. Water temp is so misleading as in new cars it rises so much quicker than the oil temp. Shed-loads of owners must misinterpret the two and start ragging once the water temp is nearly at 90, not realising the oil temp may be as low as 50 degrees. In the 8P the oil temp was buried in the DIS menus, and when selected only stayed up for about 5 seconds before it reverted back to main screen. It couldn't be selected permanently. As a general rule of thumb I would never exceed 4000rpm in my car for at least 7-10 minutes of first operation (ambient air temps depending), but after that it's fair game.