I actually did that glove test and think I have a clogged pcv system, I know the previous owner did do the oil changes consistently but might have not used synthetic oilOil filters: Mahle is OE, but you'll be fine using Mann or Hengst (both are OEMs for other makes) as well.
Oil: synthetic 5w30 or 10w30 due to the PCV system on these cars. Change regularly (every 5k miles?) to avoid issues down the road.
Also, some brand's (eg Mobil 1) 10w30 oils have very similar viscosities as 5w30 but with less viscosity index improvers and volatility. I would choose the 10w30 in these cases.
It seems that regardless of what is used, the oil has to be changed early enough to minimize the chance of vapours clogging up the PCV. This will depend on the type of driving you do as well; short city trips are brutal on oil and warrant shorter change intervals.I actually did that glove test and think I have a clogged pcv system, I know the previous owner did do the oil changes consistently but might have not used synthetic oil
It's a must on turbo engines. NA can get away with conventional since it's a lot easier on oil...and just recently went to partial synthetic. Just had to do the PCV service on my turbo. If full synthetic is preferred, count me in.