Hello Rico,
Like Bastian already suggested, indicate more precise (city/village) where you live, so that members who live close by (over the border) can contact you.
Oil consumption is not unusual for a 4.2, although the later ones ('93/'94) should be better in this respect. How many km's did yours do?
2 liter /1000km is not extreme, how did you measure? I ask, since some overhere are of the opinion, that the difference between min and max on the dip-stick is less than 2 litres.
I am not a mechanic myself, but I understood, that the timing belt change on the V8 is not a straigtforward job. You are advised to use the special tools, instead of marking the respective engine parts with paint.
In the meantime you can find a lot of material on the "Zahnriemen" (ZR) through the searchfunction, since you read German.
Veel plezier,
Eric
