My audi has now done 10600 miles and ive had to top it up with oil a few times since it was brand new in Feb this year. The dealer gave me 1 litre of Shell Helix Ultra VX 5W-30 oil when i bought the car and ive used it all now. Is this the right oil for a 2.0TDI? I need to buy some more oil as its now all been used. Thanks.