Hi
I would use a 5w-30 oil
http://www.opieoils.co.uk/c-653-5w-30.aspx
The best ones there are the Fuchs/Silkolene Pro S, Motul 300V, Mobil ESP, Castrol Edge, Shell Helix Ultra ECT, Millers XF, Fuchs GT1 and Red Line, but the Motul Eco-Energy, Mobil Super 3000, Shell Helix HX7 AF/AG and Fuchs...