To run in use a 10w-40 semi synthetic (they are all 100% mineral base) and run for around 1000 miles. Something like the Fuchs XTR 10w-40 is ideal
http://www.opieoils.co.uk/p-990-fuch...ngine-oil.aspx
Once run in a 5w-40 synthetic, if the car is for race use then look at the ester based synthetics such as the Silkolene Pro S or the Motul 300v
http://www.opieoils.co.uk/c-656-5w-40.aspx
Cheers
Guy