This a topic that loves a good discussion. Try a search on the Bobistheoilguy.com site for lots of opinions from some good guys that know way too much about oil. Personally, I use the Redline 5w-30 synthetic, but others use Mobile1, Castrol, Pentosin, and Amsoil in the weights as recommended in the manual. The big thing for the 1.8T is protecting the turbo, and protecting on startup. Some say Dino oil (conventional oil) cokes up in the engine gradually restricting oil flow.
I guess the main thing is to not fall for the I'm not sure which "oil of the month" is in my car at Pronto Lube. I say (and this is just my opinion)..use a good synthetic oil, a good filter (OEM, mann, K&N, Napa) and change the oil regularly and you're ahead of the game. Then choose a weight based on where you drive and what kind of driving you do.
If you are still using Dino oil and have some miles on the car you might want to consider AutoRx (also on bobistheoilguy.com)
Good luck in your search
