Check the oil level
Getting the Oil level correct can be tricky, and the key is to just take it really slow when adding any. Wait and re-test, never add much at once and ideally leave it a day before adding any more. Oil removal is an EPIC job, adding slowly is much easier and safer!
Notes about how the readings are taken
The McLaren system uses a capacitive sensor to measure the amount of oil in the scavenger tank (not the sump obviously as it is a dry sump).
Things like water content, sloshing of the oil, and aeration (caused by running a test, ironically) can cause different readings if done back-to-back.
Also the sensors themselves are not perfect. It will have to take several readings over like 30 seconds and then average them out.
It's not exactly this sensor, but i'm led to believe it's very similar: capacitive-oil-level-sensor.pdf
Step 1 - Check under the correct conditions
As per the manual, the car has to be LEVEL and the oil must be at the CORRECT TEMPERATURE
All going well, you'll be met with something like this:
Step 2 - If you need to add some
Firstly - there is a chart in the manual which gives a guide for the volume of oil to add based on the reading provided by the results of the check.
However, I would honestly add a maximum of 0.25 at a time no matter what the reading and then re-test later - because the last thing you want to see is this:
