ah I think I am making words up here, sorry.

Pretty sure I filled up to 2 mm above the hatched area (B area as you say?), which I have called Max. Should have taken pics of each measurement of course.

Now the level is at the top of the hatched area. So on 500 km it has dropped 2 mm on the stick. Does that make sense?

That is a good starting point. Now note the milage (or kilometers) and then do the same when the level has reached the bottom of the hatched area. This is point C on the diagram in your cars' handbook.

Calculate the distance travelled. Then add oil to just reach the start of the hatched area. Note how much oil was added and then work out the rate of oil consumption.

thanks, really appreciate it

Also, make sure your car is level when you check the oil.

My block is sloping and it's a PITA to accurately check oil levels.