My 2013 M3W was often driven in hot conditions and had to suffer stop and go traffic at temperatures close to 40°C. Never went to skip fire mode (I do have the city drive fan installed)
I wonder if additional oil cooling is needed at all. Good quality oil will do the trick I assume.
If the cooling kit was installed correctly with the re-flash of the ECU then the fan works automatically and skip fire is actually disabled. I think you're right about the good oil: with 6 litres of synthetic oil and 3000 mile changes hot oil isn't really a great problem.
