Hello Andrew,
Welcome, and thanks for joining.
Re. 0w/20 vs. 5w/30, have you consulted your handbook to see what specification is recommended there? I would take that as the bible.
Incase it helps, I have been using Quantum oil in our humble A3, over it’s now 170+K miles.
Quantum is/was VAG’s recommended brand so I’ve always stuck with it, and my routine has been to use their Longlife grade, and change it annually, even though the car only covers approx. 7K miles in that time.
‘24 month service schedule’? Far, far too long an interval in my book, even using Longlife oil. With the advent of stop/start etc. modern oils get a hammering, but it’s understandable that many car manufacturers use extended servicing schedules. As with crazy ( in my book) extended limits for cambelts etc, manufacturers are become less interested in revenue from servicing, and hanging their hats on the far more lucrative market of selling more vehicles, and appear to have less interest in making sure vehicles are maintained in respect to their longevity.
Kind regards,
Gareth.
p.s. Quantum is believed to be a subsidiary brand of Castrol.