I also have a BMW Z3M. It specifies an oil temp of 140 degrees before exceeding 4000 rpm. After watching the rate the oil warms up relative to the car I wait a lot longer on the S before exceeding 6000. On a cold day it can be 7 or 8 minutes after the car reaches full water temp before the oil reaches 140. On a hot day it is not as bad but still 3 to 4 minutes after the water is right at normal before the oil hits 140. The 3 bar limit is an emergency safety device designed for idiots. It does not mean the oil is properly warmed up.

 

mmm....Z3M, sweet car

 

i would never drive my car hard unless i had atleast 5 bars