Mobil 1 Motorsport grade (Same price as ordinary).
Any other fully synthetic, if worried about price (Eg Vaux). I change it when it gets dirty looking (4000 miles or so). Let the car idle for 20 secs before pilling away slowly in the morning.
I used to use the vauxhall fully synthetic, but at the moment i'm running useing castrol GTX semi synthetic. I dont notice any diference to be honest. I'll probably stick with the semi as its cheaper. Yet to find an oil that stops rattley tappetts, although i may try sticking some slick 50 in next time round.