We've all been programmed to check our oil level at the dipstick when the car is up to operating temperature and idling on level ground. What I'm hoping someone can clarify for me is this: it is often suggested to only check the oil once the oil lines to the front-mounted oil cooler are warm enough for the external thermostat to open and send oil to the external cooler. Is this simply so the oil can be checked when the entire oil system is in 'the loop'? Some threads seem to suggest that there will be more oil in the engine and less in the tank before the external thermostat is open, so an accurate oil level will only be obtained once the tstat opens. I don't quite understand how that can be the case given my (poor) understanding of the Carrera oil system outlined in this diagram:
Can someone explain why there would be relatively little oil in the tank prior to the external tstat opening?