Id personally run penrite hpr 30 in winter and hpr 40 in summer
i wouldnt reccomend using mobil 1 on a used turbo engine as i think it runs them "too" clean...and you can end up with glazed bores and all sorts of dramas. Its designed for new engines to keep them clean and running well - its synthetic oil remember.
Mineral oils such as penrite will keep it running the way it is supposed to.
blake
I may end up using mobil 1 or something similar in my v8 yet - the engine is brand new, so i am going to be seeking advice on appropriate oils first. I was told about a BM oil, but its $14/ Litre. And when mine will take about 9L im not gonna be wanting to spend quite that much