The turbo's in the S3 and A3 1.8T get HOT, very hot. The oil in your car has to endure, and provide lubrication, in a wider set of conditions than a NA car.
You want your oil to clean and protect your engine right from cold through 'til the engine is at full operating temp and beyond. After all when 'giving it beans' on full-boost your oil temp *could* get to 120degC and be lubricating a turbo that is hundereds of degrees hotter. So all in all a wide and harsh range of conditions.
I use 0w40 Motul E-Tech 8100. An ester based, fully synthetic oil.
The 40 bit means it is VERY good at lubricating at high temps, in fact the esters are fully sheer stable so it's 'better' in that respect than Mobil 1.
The 0w bit relates to flow, 0w flows better than 5w. This means you also get good cold start protection.
How do they achieve cold and hot protection? Well that's because it's fully synthetic and the blend of oils used 'can'
My synthetic chemistry is probably worse than my organic so i'm happy to trust them
Finally, this Motul oil is approved to VAG 503.1 so Audi think it's good enough for the engine they designed and in reality it far exceeds their minimum requirements. A good job as my engine is producing more power than Audi or it's service schedules intended.
Finally, 'long life' oils are something invented to please fleet managers who love the idea of only servicing their fleet every 20k. Especially when they only have to run the car for 60 - 80k after which the state of the engine is someone elses problem. In the real world these engines should be good for 150K but don't count on it without regularly changing the oil with a quality, fully synthetic brand suitable for your driving. By regularly i mean every 6 months or 5k.
