Either 5-30 fully synthetic or 10-40 part synthetic - £17.50 for 4l.
If you spend £50+ you get a voucher for £10 you can spend on what you like too.
My 95k miles Mk3 got the 10-40 today and it works a treat. Much smoother and quieter. I don't know what was in there before but the difference is remarkable.
Will change it out in around 6k miles though, being pretty much a mineral oil.
