I've been running Mobil 1 0W-40 since I've had my Mini. No complaints and see no reason to try anything else. Especially with the rebates they've been running. Usually pick up two 5 quart jugs in the spring and the fall. Just got my rebate checks for $24 for the spring purchase. Net cost per quart = $2.20, and it's good oil. IMO
My thought is I would burn less oil if it were thicker, whether this is true I haven't been able to find out. I do know a thinner weight oil gets hotter than a thicker weight oil.
The sound went away on it's own a few hundred miles after my walnut blasting of my intake valves and I turn off the AC now 10 seconds before turning off the engine. I don't believe it was because of the AC because it wasn't always on, but thought it would be a good practice anyway to not leave the AC on when turning off the engine. My IAT's were high enough (140F, 30 min) after sitting in my driveway on hot Summer days when starting it back up.