Which oil do I need?

Not sure which engine oil to use for your car?

Castrol have got this very nifty tool which tells you exactly which one to use by looking up your registration number.

http://www.castrol.com/castrol/iframe.do?categoryId=9024084&contentId=7044829

My findings:

Jaguar 3.0 V6 = 5w 30 - Fully Synthetic
Audi Q7 3.0 V6 TDI =  5w 30 - Fully Synthetic
Vectra Dual Fuel SRI = 10w 40 - Part synthetic
Mercddes C220 Diesel = 5w 30 - Fully Synthetic

So the Merc and the Audi can share the same oil, though the velocity of the oil in the Jag is the same I probably should use a different one as it is a petrol.