It says VW 500 00 or VW 502 00.
Quick google brings me to http://www.opieoils.co.uk/c-744-vw-50000-oil.aspx where they have 10W40 which is what I bought. Are there any differences between the brands?
Mixing oils is not ideal, but neither is putting in 5L+ of the correct grade and mixing it with the several years worth of crap contaminated oil that is leftover in the engine even after putting the sump plug and filter, but I'm sure none of the "OMG, Read the Manual!" crew even think about this when they book their car in for an oil service.
They should flush out all the oil when doing an oil change, not mix it with whatever crap is in there at the time
How hard would it be to do that?
Not quite sure what you mean?
Engine flush can cause more issues than good..
Engine flush can cause more issues than good. Unless you are suggesting I dismantle my whole engine, have it chemically cleaned and reassembled?
Regular oil changes with the right grade and ensuring the level is correct is more than enough.