[roundle]

If I were in the US, I would probably use one of the following and change it every 10K miles:

* Castrol Syntec European Formula SAE 0W-30. This is one of the few true 'Group IV' (PAO-based) synthetics sold in that is readily available and cheap

* Mobil 1 SAE 0W-40. While a 'Group III', rarely do you hear bad things

*BMW Branded Castrol (Group III, branded 'Softec' in Europe) or Shell are both good but you are probably paying a premium for the re-branding

If I had just bought a used car, and the engine were dirty, I might be tempted to run a couple (2500 mile) cycles of a true 'Group 5' synthetic like Redline or Motul 300v -- these both have loads of detergents and do a nice job 'cleaning'.