I have to disagree with the above. There’s no mention of OE parts or vat registered garage in the above link. I’ve had a few cars from new and have serviced them myself. I also got confirmation in writing that I could do this (Ford and VW). Yes, I used OE parts and kept the receipts but OE parts are not necessary. Under block exemption, there is no need to use a vat registered garage or OE parts. You have to use parts of 'equivalent quality' and should a warranty claim be refused because non OE parts were used, it is down to the manufacturer to prove they were not equivalent quality and not for you to prove that they were. The servicing has to be as per the manufacturers standard and they can’t, for example, refuse a warranty claim for say, a failed alternator because you used the wrong engine oil as they are not related. Most manufacturers customer care departments will confirm this and will often email you a service sheet to follow - how else are you supposed to follow their recommended service requirements without one?