Hello Chris and Trevor,
My good lady has recently acquired our daughter's 2006 owned from new, now 138k. A3 Sportback 1.6. This car has always run on Longlife Quantum 5w/30 as recommended by the VAG dealer where we get all the service items from.
Now that it will only be doing modest mileages with us, I've decided to service it annually and this time used Mobil 3000 5/30 fully synthetic ( to Ford spec.) which I get at Wilkinsons at £24 for 5 litres. Apologies for contradicting, but I would not use a 0w/30 in these cars, and I'm sure you will find that this is not the grade recommended by Audi for this car. Worth checking your handbook? This car has always run on Audi filters which we get on discount from Skoda Parts shop ( up north somewhere but the exact location evades at the moment). No connection with this business, but we have found their parts service is first class.
Re timing belts and water pump. This car has been on its second Audi cambelt kit since 110K. OK changed early, but not worth taking a chance. Again these kits can be obtained on discount, but if I was going to use aftermarket then I would only use Gates.
Water pumps:- I would never use an aftermarket pump since there are too many stories of failure, often after short mileage. When thie belt kit was changed at 110K, the original pump was policy changed at the same time, using a main dealer part, which if I recall was a reconditioned exchange unit.
Not sure if any of this helps.
Good luck and kind regards,
Gareth.