Regards Oil, I use Castrol Edge in my ED30 (one of the recommended by VW) 5W-30, I bought a 4L can for my garage and have one of the 1L bottles in my boot (in one of these VW cases which is velcro'd to back of the rear seat), It's handy and keeps it out of way and is there should you need it, also includes some rubber gloves and paper funnels to guide it in if your not of the "Steady hand brigade".
Cheapest place i think is your local Asda £35 for 4L, tesco does Castrol Edge but I did not see 5W-30, only other viscosities.
If anyone knows cheaper post it up for the guy!