I use motul 8100, its very similar to mobil 1, better somehow (what i was told my a oil salesman, with a whole heap of fact sheets) its similar in price too. I have used mobil 1 too and i cant tell the difference, but one thing that i can say, is that, there is no way that i will put mineral oil into any car that i own. Your car is a big investment, so why skimp on a measly $30 or so on getting the cheaper stuff. Your car is worth way more than that.

I have also put in a k & n, its well worth it too, not just for peformance or economy reasons, but also for the simple reason, that if you do a bit of driving on dusty roads or in sand its much easier to clean. I have got so much sand out of my filter before, i made a castle with it.

another simple upgrade that i would recommend is spark plugs. I have put in NGK iridium spark plugs. I have heard that the original ones are meant to be good, but these are definately way better. Not cheap though, over here they are AU$22 each compared to AU$4 for a standard plug. Engine runs much smoother too.