I'm using fully synth, Millers 5W/40 in mine.
You can get it from TDI North, £33 for 5 litres.
Silkolene Pro S also comes highly recomended and many ppl here including myself use it. My car was serviced at Powerstation and I think they put 10w-50 in.
Opie Oils on here does some pretty good discounts if you can't source any locally or cheaper.