Well said - DC - and in perfect english, as well!
Germans are so shy to speak or write in english, although most of them learnt it in school, at least in the old Bundesländer since really long ago. Hence it is nice to see a little cross border communication and help with typical car problems...
In the E OPC community there is often the talk of the different oils Opel recommends, so a couple have shifted to other brands. One often chosen is Ravenol, who offer LS specific oil with explicit Drexler approval. In detail these two are used mostly:
SAE 75W-140 Racing Gearoil
SAE 75W-90 RHP Racing High Performance Gearoil
The first is not that well in cold or icy conditions, but holds up to high temps for extreme use.
In case you want to consider an alternative to the Opel jungle of confusion, try out Ravenol.
I've been using their engine oil for two years now, and I'm keen to recommend this brand due to the experiences I made. 