U are right on 5000 and 9000.
So its logical for 7000 to be semi even i hav never see or use it b4.
On the 15w-50 and 10w-50,i agree to that the viscosity is not much different but the engine never lies when it does not like the oil.
If not can save a lot in maintenance cost on the 1.8.
I'm considering to run my BLM on the Quartz 9000 10w-30 when i want to stop sending to sc.
U think it can handle it or is it too thin?
If not maybe 10W40.I'm aiming for good fc.
So far engine does not consume oil.Plug oso dry.