Audi Repair: engine overheat or something else?, tow questions, audi v8

Question
Dear greg
tow questions: 1. how many liters of engine oil should i fill to Audi V8 Qattruo 1990 3.6L \ the service guy fill it with almost 9 liters and i think this is abnormal ?

2. after i had your answer about the engine overheat i replaced the thermostat, now the condition is as follows : the engine starts very smoothly without any problem and would stay so whether the car is running or stopping, but once the heat gauge would reach up to 80C the engine stops running or shutdown, electrecians and mechinics examined the engine once after the shutdown of the engine and they had noticed that no fuel would come up as well as no charge, but if i would leave the car to cool down in about 30 min to restart the engine it would run as normal car to last runnig for almost the same period. i have changed the fuel pump as i told you but the problem is still thier. all what i think is that there is some relation with the engine heat and somewhere i mean if the heat would reach up to 80C a signal from somewhere would go to somewhere to cut down any electrical charges to the engine as well as the fuel pump to stop pumping fuel untill engine's heat cools down.

Answer
I'm sorry but I'm not that good with older cars. I only have seen 9 liters on new 4.2 engines(2005-2006).
Same thing with your enginr problem, Idid not have time look in older wire diagrams, and I have no idea what is the problem, SORRY. I will try to pull them out this week.
good luck             pltech