oilman said:5w-40 is ideal grade for the car, its not too thin at all. Infact you should find it listed in the handbook.
The Halfords own is not a true synthetic but a hydrocracked mineral oil, just moving to a genuine synthetic should yield an improvement.
Have a look at the Fuchs Titan Supersyn SL 5w-40.
Cheers
Guy.
Cheers, and thanks for the email as well. Much appreciated!