Bit of a cross post but I'm pleased to say my 12 quid Silverline extractor did the job and I did find the right dipstick tube. I was a bit heavy handed with the pump and creating a vacuum and had I not kept an eye on it it would have pulled out 1.5L not 1L. I say 1L as that's what it looks like approx. as the container is 1.5L but there are no markings on the side of it ... Anyway, dash seems happy, the car's still barely done any miles, and for a C55 yes it is the red flat end cap to the rear left of the engine as you stand in front to extract the oil!