Hi Guys just had a big service done (£279) at my local VW dealership on my 55 plate GTI with 62k, noticed on the invoice that they've used Castrol gtx 10w40. Is this VW approved for the GTI? Always thought it should be fully synthetic 5w30 or something? Didn't expect them to use the cheapest option available? Was invoiced at £42+vat for it too, the robbing feks, asda sell this for £20 for 4ltr.
Should i complain or will it be ok?