Recommended Filter for 2002 XK8

[londonxk8]

hello - my neighbor (an ex mechanic) has kindly agreed to do my Oil and filter for me. Any recommended model/brand for a filter? i would likely buy online. 

for the Oil i went to halfords and bought Castrol magnatec 5w30 a5, but was £12.99 for 1L - which he said is very dear. so will look for a cheaper price online!

[londonxk8]

hi all. want to change over the Oil in my 2002 xk8. when i put in the registration, getting different recommendations for Oil (with big price differences).considering i will change it over every year (not doing more than 3k miles/year), i think cheapest option should be OK. question is, can i use any of the following oils (will go with castrol):

- Castrol Magnatec 5w30 fully synthetic

- Castrol Magnatec 10W-40 ACEA A3/B4 Semi Synthetic Car Engine Oil - Service Pack: 8 litres

so confused as it if i can use 5w30 or 10w40?