I would use a 5w-40 synthetic for both cars
http://www.opieoils.co.uk/c-656-5w-40.aspx
Out of those, the best ones are the Silkolene Pro S, Motul 300V, Redline and Gulf Competition. The Motul 8100 X-Cess, Gulf Formula G, Fuchs Supersyn and Mobil Synt S are good, cheaper alternatives. Go with one of the good oils in the track car and either will do for the road car
As a budget choice, for the road car, a 10w-40 will be fine and I would either go for the Fuchs XTR or Motul 6100
http://www.opieoils.co.uk/c-657-10w-40.aspx
Cheers
Tim