All S65 motors came from the factory with an oil filter housing meant to limit the flow of oil to the cooler.
BMW did this intentionally so that when your engine Is cold the closed thermostat allows the oil to heat up quicker.

While BMW may have had good intentions, this causes overheating issues in S65 motors.
Even at operating temps this thermostat is extremely restrictive and will not open all the way!
This has caused headaches for many S65 owners.