6k oil changes in itself is the best thing you can do for your car, using the best brand is less important. Make a list of brands you are happy to use and keep an eye out throughout the year for sales. Opie Oils typically have great sales and offer forum discount!
That’s why I went on a vw service plan at £20 a month you don’t notice it coming out, then you can pay for other oil changes at independents etc just buy a vw service schedule book to keep the stamps in. I average about 2 oil changes a year at this point but it was 4 in my old GTD, but my GTD sounded as smooth as my GTI when i sold it.