[DSPTurtle]

I run Mobil 1 15/50 since they don't make 20/50 any more. As for pressures, the reason I switched to only synthetic is that one day after making a few hard runs on some Valvoline 20/50 the gauge dropped to 3 bar. I immediately went to Mobil 1 and since then the gauge has stayed pegged at 5 bar (except when shifting where it is supposed to make a little blip) until I had a track day last month and it ran around 4-5 bar for the last two sessions. There is nothing wrong with it being pegged on 5 bar. Higher oil pressure is better from my experience with my 944. It is not like the 911 that makes 1.0 bar per 1,000 RPMS... totally different oiling system.
Yes, Castrol is a little cheaper, but I have tried most of the stuff out there and Mobil 1 is the only one that keeps full oil pressure even after running extremely hard.