I used castrol magnatech and was happy with it, now using penrite 10w 60 which is good, but magnatech was better. I don't think you'll notice too much difference from different oils, so long as it's clean it should do the trick. I have tried more expensive synthetic oils (the ferrari shell oil and mobil 1) but imo they make the engine feel flimsy. A mineral/synthetic blend keeps the bottom end feeling solid imo but is probably just all in my head (nothing scientific), remember the oil is there to form a barrier between metal surfaces, so thinner is not always better.

Mobil 1 for me

Muz, what weight oil are you using?

Castrol Edge 10w - 60 for me.