15w/50 mobil motorsport mate, i take the previous point about it only being sold in 4 litres, but it costs at the most £50 to do an oil change, costs around £ 4k to rebuild an engine, personally i never take the risk, never let the level get low and change every 3k.

These engines are basically racing engines and are designed to consume oil (up to 1 litre every 600 miles) !!! as stated in the workshop manual, and that's a standard motor !!!

never used castrol before but once you've starting using one oil and had good results why change !!!!

regards,

paul