Just thought I share my experience so far with the above.
I had been using Mobil 1 engine oil in the Clubman since I first purchased it 18mths ago. Done 143000 when I first got it, now has 149000ks.
Before every track day I would change engine oil and filter, diff and gearbox oils and flush brake and clutch systems. Also every 12 mths coolant.
Probably overkill, but I work on trucks all day I don't need any hassels from the toy.
So during the last track track day of 2008, the oil pressure dropped during the 5 lap runs and would come back when the car cooled down, not happy Jan. This oil (Mobil 1) is supposed to be the bee knees. Took a sample when I got home and asked Mobil if they could test the oil and tell me why the oil broke down under hard load. Long story short they basically told me to change the oil and try it again!!!!!

Now if I'm paying top dollar for an oil that is supposed to be able to do the job, I expect it to do the job or for the manufacturer to back up its product. Not too much to ask in my opinion.
Now I needed a new oil supplier for our fleet of Jap trucks. Enter Valvolene, spoke to the rep and asked him about oil for the Clubby. He suggested Full syn engine oil, and use the diff and gearbox oils I use in the trucks.
First impression after changing the engine oil, engine quiter but I would expect this. Engine temp going out to QLD raceway was about 3 needle widths lower than it's ever been. So did the runs all day and the oil pressure out on the track ran around 6 under full stream, and half way at idle when came in to the pits. Oil usage was zero. Oh! by the way my car has a proper oil guage.
So far I'm a happy chappy and this oil cost me a lot less than the Mobil 1.
Terry