I agree that it's both important to use the OEM/Mann filter and to perform oil/filter changes at regular intervals. You probably can't go wrong with either Mobil 1, Syntec or any other reputable synthetic. The way I look at is it that a reputable synthetic well exceeds any conventional oil. I'll have to disagree with Consumers Reports that there is no benefit is using synthetic over conventional oil. Consumers reports used taxi cabs and they were were typically kept running all day. Common knowledge that the majority of engine wear is during cold starts, especially during extreme sub zero temps that causes conventional oil to congeal. There are well known benefits is using synthetic, especially with a turbo. I go by Volvo's recommended 8,000 km interval, however in the winter I change it at 4,000-5,000km. My daily commute is only 6km and the car is kept idling a lot, so the oil gets contaminated a lot sooner. Synthetic oil is superior but can still be affected by contamination. I've been using Castrol 5W-30/10W-40 in my 98 S70 T-5, which currently has 126,000km.